Attenuated poxviruses have been developed for use as candidate vaccine vectors. ALVAC, a strain of the Avipoxvirus canarypox, has been extensively evaluated as a vector for vaccines against the human immunodeficiency virus type 1 (HIV-1). This report presents the safety and reactogenicity data derived from 11 multicenter, randomized controlled trials of ALVAC-HIV vaccines conducted by the HIV Vaccine Trials Network (HVTN) and its predecessor, the AIDS Vaccine Evaluation Group (AVEG). Five different ALVAC vaccine constructs were tested among 1497 volunteers. Reactogenicity was similar for different ALVAC constructs. Local reactions of any grade to ALVAC vaccines were common. However, fewer than 2% of vaccinees had severe local responses, and less than 1% experienced severe local pain or tenderness. Systemic responses were mild and transient. As combination vaccine regimens are in common use, we also evaluated side effects of ALVAC vectors given in combination with a recombinant subunit protein. No significant differences were noted in the reactogenicity of ALVAC given with or without a recombinant envelope subunit vaccine. Black, non-Hispanic and male recipients of ALVAC-HIV reported less pain following vaccination than White, non-Hispanics and females, respectively. ALVAC-HIV vaccines are well tolerated at tested doses. The reactogenicity profiles are comparable to those reported for existing vaccines licensed for use among adults. Reactogenicity does not appear to be related to the number or type of inserted genes, and did not vary between different ALVAC constructs.