Eleven cases of cryptococcal meningitis were diagnosed and biotyped from September 1991 to August 1992 in Papua New Guinea (PNG). Seven isolates were Cryptococcus neoformans var. gattii from paediatric and adult patients, one with diabetes mellitus and 4 were C. neoformans var. neoformans from adults, of whom 2 had human immunodeficiency virus type 1 (HIV-1) infection, and one each had tuberculosis and Plasmodium vivax malaria. Significant clinical findings were headache, fever, meningism, vomiting, photophobia, papilloedema and cranial nerve lesions. Five patients (45.5%) died; 3 of these were adults with var. gattii and 2 were men with both var. neoformans and HIV-1 infections. This prospective tropical study documents the emergence of C. neoformans var. neoformans in patients with HIV-1 infection in a country where previously var. gattii had predominated in the immunocompetent. There has been no earlier report of cryptococcosis in an HIV-1 seropositive patient in PNG. Despite presumed exposure to both varieties of C. neoformans, var. gattii infections had been most frequent. As HIV-1 spreads, the proportion of hosts infected with var. neoformans may rise. The course of meningitis caused by the 2 varieties of C. neoformans may differ, with mortality in the tropics remaining particularly high. In PNG the environmental source of C. neoformans remains elusive.