We have expressed fragments of the cDNA coding for mature human interleukin-1 alpha (hIL-1 alpha) in Saccharomyces cerevisiae. Mature hIL-1 alpha contains one potential N-linked glycosylation site that is not recognized in mammalian cells. Translational fusions to either one of three yeast signal sequences resulted in secretion of bioactive, N-glycosylated hIL-1 alpha. The extent of glycosylation was significantly reduced using the alpha-factor signal sequence, which itself contains three N-linked glycosylation sites known to be core glycosylated. N-glycosylation has no effect on biological specific activity.