There is a number of specific infections due to opportunistic mycobacteria which normally exist as environmental saprophytes. Among them, renal mycobacteriosis is a disease similar to renal tuberculosis. The obvious causative agents are some mycobacteria: Mycobacterium chelonei, Mycobacterium fortuitum, Mycobacterium xenopi, Mycobacterium kansasii, Mycobacterium avium complex, and Mycobacterium simiae. It is not easy to prove that a renal disease is of mycobacterial origin. We suggest some criteria as revision of Davidson's sign that help establish the diagnosis of renal mycobacteriosis. The aim of this paper was to review clinical features, diagnosis and treatment of renal mycobacteriosis, illustrated by presentation of a case of pyelonephritis and cystitis caused by Mycobacterium chelonei. Successful chemotherapeutic regimen was largely based upon our own experience as well as on the limited information in the medical literature.