From November 1995 to October 1997, seven patients with invasive infections due to Rhodococcus equi were treated in Taiwan. Four patients had pulmonary lesions, and one each of the remaining three patients had a recurrent Port-A-Cath (Kabi-Pharmacia, North Ryde, New South Wales, Australia)-related bacteremia, a primary bacteremia, and a brain abscess. Three patients had underlying hematologic malignancies, and one each of the remaining four patients had diabetes mellitus, Waldenström's macroglobulinemia, long-term use of steroids, and AIDS. The 13 isolates of R. equi recovered from these patients were identified by using API Coryne System (bioMérieux, Marcy l'Etoile, France), VITEK GPI card (bioMérieux Vitek, Hazelwood, MO), supplemental biochemical tests, and cellular fatty acid chromatograms. Susceptibilities of these isolates to 16 antimicrobial agents, with use of the agar dilution method, varied; among them, amikacin and trimethoprim-sulfamethoxazole were the most active agents. Different random amplified polymorphic DNA (RAPD) patterns of isolates from different patients documented the lack of epidemiological relatedness of the causative organisms of these infections. This study confirms the emergence of multidrug-resistant R. equi infection in Taiwan and documents the relapsing or reactivating nature of this infection.