To evaluate the incidence and survival time for AIDS-patients affected by different stages of nontuberculous mycobacterial (NTM) infection we performed a retrospective study. Data of 1540 hospitalised AIDS-patients was analyzed with respect to survival time and incidence rates. The overall incidence rate of NTM following AIDS was 16.6/100 person-years (PY), with an increase from 12.1/100PY (1987-1990) to 18.9/100PY (1991-1994). Antiretroviral therapy (ART) and toxoplasmosis prophylaxis reduced the risk of NTM disease whereas CD4 cells <40/ microl at time of the first AIDS defining illness led to a 2.5 fold higher risk. Pneumocystis carinii pneumonia (PCP), wasting syndrome and PCP prophylaxis increased the risk of progression from colonization to dissemination. Cryptococcus neoformans infection, wasting syndrome, PCP prophylaxis and CD4 cells <40/ microl were linked to immediate NTM dissemination. Though the incidence of NTM dissemination increased by the factor 1.56 in 1991-1994, survival did not differ between patients with and without NTM infection.