An 11yr-old female Pacific walrus (Odobenus rosmarus divergens) demonstrated decreased appetite and weight loss approximately 4 wk after truck transport from a northern California facility to a southern California facility. An initial blood analysis revealed a leukocytosis of 22,800 white blood cells (WBC)/μl, with a left shift, low iron (58 μg/dl), and mild hyperglobulinemia (4.3 g/dl). Empiric antibiotic therapy was started with amoxicillin and clavulanic acid (14 mg/kg p.o. b.i.d.). Clinical improvement was observed initially; however, follow-up blood analysis demonstrated a persistent leukocytosis (24,000 WBC/μl), with left shift and progressive hyperglobulinemia (6.7 mg/dl). As a result of the relapse of clinical signs on antibiotic therapy, aggressive antifungal therapy was initiated with voriconazole (1.8 mg/kg p.o. s.i.d.). Concurrent fungal immunodiffusion antibody assays and complement fixation were repetitively positive for coccidioidomycosis. The walrus improved clinically over the next 3 mo and is currently stable on antifungal therapy at its originating facility in northern California.