ObjectiveTo describe patterns of health-service usage and the resulting costs in 1992–1993 for Australian men.DesignA prospective survey, stratified by phase of illness.SettingHospital and community-based care.PatientsA total of 128 homosexual men: 20 in phase 1 (CD4+ count ≥500×106/l), 31 in phase 2 (CD4+ count <500 and ≥200×106/l), 30 in phase 3 (CD4+ count <200×106/1), and 47 in phase 4 (AIDS).Main outcome measuresMean monthly service usage rates and costs.ResultsHealth-service utilization increased and became more hospital-based as illness worsened; the main exception was use of antiretroviral drugs, which peaked in phases 2 and 3. Hospital admission was rare before diagnosis of AIDS. Hospital bed-days per patient per month averaged 3.3 for AIDS patients until the final 3 months of life increasing to 15.8 in the 3 months before death. Mean monthly costs (in 1992–1993 Australian dollars) were $331 [95% confidence interval (CD, 218–455] in phase 1, $677 (95% CI, 540–836) in phase 2, $1372 (95% CI, 1044–1776) in phase 3, and $4615 (95% CI, 3456–5985) for AIDS patients until the last 3 months of life and $13 308 (95% CI, 10538–16516) in the 3 months before death. Drugs comprised 57% of total costs in phase 1, but only 30% of costs for patients with AIDS, whereas hospital bed-days comprised 10% of phase 1 costs and 60% of AIDS costs.ConclusionsHealth-care utilization and resulting costs increased with severity of illness, and were particularly high for AIDS patients in the 3 months before death. Service-utilization patterns and components of costs varied between each phase.