Children infected by HIV-1 are particularly vulnerable to severe, recurrent, or unusual infections by vaccine-preventable pathogens. Routine immunisations seem to be generally safe for HIV-1-infected children, but responses may be suboptimal. Early HIV-1-induced immune attrition associated with viral replication may particularly interfere with the development of memory responses. In high HIV-1 prevalence regions, the accumulation of susceptible hosts may compromise disease-control efforts. Although early control of viral replication through treatment with highly active therapy may preserve immune function and responses to routine childhood vaccines, availability is limited in the areas most affected. In this review, we provide an overview of the immunogenicity and efficacy of childhood vaccines in HIV-1-infected children. The possible immunological bases for defective responses are discussed; unanswered questions and the need for further research are delineated.