The good news for physicians treating patients with advanced AIDS is that both prevention and treatment of disseminatedMycobacterium avium-intracellularecomplex (MAC) infection appear to prolong survival. The bad news is that an increasing number of MAC strains are developing resistance to clarithromycin, one of the most effective drugs used to manage this infection. These and other issues relating to MAC infection and its treatment were discussed at the 35th Interscience Conference on Antimicrobial Agents and Chemotherapy [San Francisco, US; September 1995].