The arginase (ARG)-encoding gene (arg) of Coccidioides immitis, a human fungal pathogen, was cloned and sequenced. Both the genomic and cDNA sequences are provided. The transcription start point and poly(A) sites were confirmed. The arg gene, which was located on chromosome II of C. immitis by Southern hybridization, is a single-copy gene with two introns and a 966-bp ORF which translates a 322-aa protein of 35.1 kDa. The deduced ARG protein showed 44% identity and 68% similarity to the Saccharomyces cerevisiae ARG.