Background: Some fungi such as Sporothrix Schenckii may rarely cause arthritis. A 36-year old woman presented with complaining monoarthritis of right knee. Sporothrix Schenckii was revealed in the joint effusion for the first time in Iran.

Case Report: She received ketoconazol, 400 mg daily in two divided doses. During the treatment functional liver test and other necessary laboratory tests were evaluated every month.

Results: After 8 weeks, effusion, pain and movement limitation decreased. After 2 months, some yeast was seen in microscopic evaluation of sinovial fluid. Six month after treatment, pain and swelling completely disappeared.

Conclusion: Based on the result of this study, Ketoconazole is recommended as choice treatment of sporothrical arthritis.