History and Objectives: Due to the prevalence of the arthritis and probability of mycotic nature of some of the arthritic cases, a patient with monoarthritis which had negative test for arthritis indices, who was non-responsive to various medications, was referred to the Mycology Department of Kashan Medical University in 1997. Synovial fluid was taken and analyzed by direct examination, staining, culture growth, injection of the suspension to laboratory animals, autopsy of the infected animal and histological examination. According to the present data, the first case of sporotrichal arthritis in Iran is reported. The patient is a 36 years old woman who was subsequently treated with antimycotic therapy and hence pain and inflammation of knee area disappeared and she did not have any restriction in movement. Therefore, it is suggested that sporotrichal arthritis is included in the differential diagnosis of arthritis.