To evaluate human immunodeficiency virus (HIV) partner notification and referral across index case groups, we analysed results of services provided by the Colorado Department of Health during 1988. Services were offered to 231 index cases; 226 (98%) accepted; 124 (65%) with unsafe behaviours identified 239 partners; 79% of partners were notified; 68% accepted counselling. Seropositivity was 21% in newly tested partners. Index cases chose patient referral for 25% of partners and referred 20% of eligible partners; the provider referred 71%. Index case acceptance of service, proportion of index cases with newly identified HIV positive partners, and choice of partner referral method were similar across groups. Gay men identified fewer partners, had a lower proportion of partners accepting new counselling and testing and referred a lower proportion of partners than heterosexual men. The total costs of the service were $19,496. Twelve new cases of HIV were identified through patient and provider referral and cost per case identified was $1625. Partner notification and provider referral should be offered to all HIV infected individuals in Colorado, as few differences across groups emerged and only 20% of located and eligible partners received counselling through patient referral.