 Niculae's form for Dinamo saw him selected for the Romania U-21 team to play Bulgaria U-21 on 3 March 1999, and he marked his debut with the second goal as Romania won 3–1.He played his first official match for Romania U-21 on 26 March, in a 0–1 defeat against Slovakia U-21, coming in as a substitute for Marius Luca in the second half.Despite he played all six remained qualifiers, Niculae hasn't scored a single goal as Romania failed to qualify at the European Championship.