Atypical mycobacteria can induce soft tissue infections such as tenosynovitis. We observed one case of finger flexor tendon tenosynovitis infected with Mycobacterium avium intracellulare and one case of knee and ankle arthritis with lateral peroneal tendon tenosynovitis due to M. chelonei. In the first patient, a tenosynovectomy only was performed leading to resolution of the infection. The second patient was immunocompromised as a result of corticosteroid therapy and the mycobacterial infection was treated with tenosynovectomy and multidrug chemotherapy. This patient died from infectious pneumonitis. Previously reported cases of infectious tenosynovitis due to these atypical mycobacteria are reviewed.