We have found that a high iron concentration in solid complete cultivation medium potentiates cell-cell and cell-surface adhesion of the fission yeast Schizosaccharomyces pombe. Spotted giant colonies grown on iron-rich media were found to be more compact and more resistant to washing than those grown on plates with a standard iron content. Furthermore, we have documented that excess environmental iron stimulates the invasive growth of S. pombe (and Saccharomyces cerevisiae). Three-dimensional, branched, washing-resistant structures composed mostly of elongated, but separate fission yeast cells, were formed within the solid agar medium. The degree of both adhesion and invasion displayed a specific, iron concentration-dependent response. Our results suggest a novel link between iron availability and the intensively studied and important fungal virulence factors, adhesion and invasion.