The practice of sampling -- electronically copying bits of sound from another artist's recordings -- is a prime element in rap music. But recent lawsuits against sampling have raised concerns that rap records in their present form will become too expensive to produce.

The challenges have some record-company lawyers thinking anew about what constitutes fair use of artists' material. Others in the music business are worried that a clampdown on sampling would adversely affect the creativity of rap artists. Sampling is central to the ethos of rap, or hip-hop, which originated in poor urban neighborhoods where borrowing bits of many songs to build a piece of music began as a necessity and evolved into something of an art form.

Aaron Fuchs, the president of Tuff City Records, a hip-hop and rhythm-and-blues label in New York, filed suit in December against Sony Music and the Sony-distributed Def Jam Records, claiming that a Def Jam recording illegally sampled a Tuff City drum track. Generally, the more successful rap artists and producers pay fees or royalties when they want to sample a melody or harmony from other artists' recorded material. But sampled drumbeats, which are usually so brief that they have not been considered a definitive part of a song, have almost always been used without prior approval. Multiple Use

Mr. Fuchs's suit, filed in Federal District Court in Manhattan, asserts that the producer Marlon (Marley Marl) Williams violated copyright laws by using a drum-track sample from "Impeach the President," a 1973 song by the Honeydrippers, for use on two singles by L. L. Cool J ("Around the Way Girl" and "Six Minutes of Pleasure") and that another Def Jam record, "Give the People," by the duo EPMD, includes vocal samples from the same Honeydrippers song. Mr. Fuchs recently bought the rights to "Impeach the President."

David Harleston, the president of Def Jam, characterized the claim as "utterly without merit." He said that the case was not currently on a trial docket, and that he had "no idea when or if it will ever get that far." A man who answered the phone at Tuff City and said he was the label's attorney, but would not give his name, said the company would not comment on a "pending legal matter."

When asked if L. L. Cool J had ever been sampled without authorization, Mr. Harleston replied that he had, but that the problem was resolved amicably.

Some lawyers and businesspeople say that if Mr. Fuchs wins, rap music -- which by some estimates generates sales of about $1 billion a year -- could become financially impossible. The cost of clearing samples, already expensive, would rise even higher with the additional cost of paying for drumbeats.

"If Aaron Fuchs wins, it could be prohibitively expensive to make a rap record," said Lawrence Stanley, an attorney who with his wife, Hope Carr, runs Clearance 13'-8", a sample clearing house. He also represents the group P.M. Dawn. "Probably 99 percent of drum samples out there are not cleared," Mr. Stanley said. "Everyone takes beats from other songs, adds things over them, amplifies them, does anything they have to do to make their own track. If Tuff City wins, it could mean you'd have to clear everything on a record." Tens of Thousands of Dollars

A single rap album can include dozens of samples, from single drumbeats to full musical phrases. Finding the copyright owners, negotiating fees or royalties and gaining legal clearance is time consuming and can add tens of thousands of dollars to the production costs.

Even before Mr. Fuchs filed his lawsuit, concern over sampling's future had been heightened by a court ruling that found the rapper Biz Markie guilty of using parts of Gilbert O'Sullivan's hit "Alone Again (Naturally)" on an album without permission. Judge Kevin T. Duffy of Federal District Court in Manhattan ruled in December that eight bars of Mr. O'Sullivan's 1972 hit had been used without clearance from the copyright holder. He pointed out in his decision that in today's business world, the admonition "thou shalt not steal" is "not always followed." Warner Brothers, which distributes Mr. Markie's Cold Chillin' label, was ordered to discontinue sales of the album "I Need a Haircut."

The advent of rap music and sampling changed notions of how music was made and demanded redefinitions of originality. An art born of the circumstances of poverty, hip-hop started in the Bronx in the 1970's at parties and in playgrounds, in basements and at community centers, where hip-hop disk jockeys played bits of records sometimes just seconds long and built them into rhythmic grooves and sonic collages behind rappers. Borrowing and manipulating other people's material was made easy by the advent of digital samplers: essentially recorders that convert sounds into strings of numbers and can play back those sounds at the touch of a key or the blip of an electronic impulse. No Clear Definitions

The technology has raised the question of what constitutes fair use -- as opposed to outright stealing -- of original recordings in rap music. The law has not been helpful in setting clear boundaries. Two kinds of music copyright are protected by law: composition (a song's words and music, usually recordable on sheet music), and sound recording (the music as recorded on a master tape). To win a copyright infringement suit, a plaintiff has to prove that there is substantial similarity between the original work and the new one -- and no court has yet ruled whether a single manipulated note is substantial enough to qualify as artistic theft.