Using genetic complementation in Saccharomyces cerevisiae, we have isolated a Trypanosoma brucei gene encoding profilin. Overexpression of trypanosome profilin suppresses defects that are associated with the loss of the C-terminal domain of the adenylyl cyclase-associated protein in S. cerevisiae. Similarly, the T. brucei gene complements a profilin-deletion mutant of S. cerevisiae. The full-length cDNA clone isolated contains an open reading frame of 150 amino acids, with a predicted molecular mass of 16.1 kDa. The gene appears to be present at single copy and is expressed at approximately equal levels in both mammalian and insect forms of the parasite.