The proportion of frail elderly people in the industrialized world is increasing. Respite care is a potentially important way of maintaining the quality of life for these people and their caregivers. The objective of this systematic review was to determine the effectiveness and cost-effectiveness of different models of community-based respite care for frail older people and their caregivers. To identify relevant studies, 37 databases were searched, and reference checking and citation searches were undertaken. Well-controlled effectiveness studies were eligible for inclusion, with uncontrolled studies admissible only in the absence of higher-quality evidence. Studies assessed the effect of community-based respite on caregivers of frail elderly people relative to usual care or to another support intervention. Eligible economic evaluations also addressed costs. Where appropriate, data were synthesized using standard meta-analytic techniques. Ten randomized, controlled trials, seven quasi-experimental studies and five uncontrolled studies were included in the review. For all types of respite, the effects upon caregivers were generally small, with better-controlled studies finding modest benefits only for certain subgroups, although many studies reported high levels of caregiver satisfaction. No reliable evidence was found that respite care delays entry to residential care or adversely affects frail older people. The economic evaluations all assessed day care, which tended to be associated with similar or higher costs than usual care. Given the increasing numbers of frail elderly people and the lack of up-to-date, good-quality evidence for all types of respite care, better-quality evidence is urgently needed to inform current policy and practice.