PURPOSE Alternative and complementary therapies are infrequently studied in pediatric populations. We performed a population-based survey to aid health care workers in identifying and counseling parents who may use these remedies. PATIENTS AND METHODS We retrospectively surveyed the parents of 583 pediatric patients diagnosed with cancer in British Columbia between 1989 and 1995. Prevalence and factors that influence the use and nonuse of alternative and complementary therapies were estimated. RESULTS Alternative and complementary therapies were used by 42% of 366 respondents. Herbal teas, plant extracts, and therapeutic vitamins were the most commonly used alternative therapies. Relaxation/imagery strategies, massage, and therapeutic touch were the most commonly used complementary techniques. Factors that influenced the use of alternative/complementary therapies were prior use (chi2 = 60.0, P < .0001), prior positive attitude towards these remedies (chi2 = 41.6, P < .0001), soliciting information from family and friends (chi2 = 70.5, P < .0001) or from alternative care givers (chi2 = 58.7, P < .0001), high risk of death at diagnosis (chi2 = 9.6, P < .002), and advanced education of the father (chi2 = 7.4, P < .006) or mother (chi2 = 8.6, P < .003). Parents who used alternative/complementary therapies did so in conjunction with conventional medicine (98%). Lack of knowledge and fear of interference with conventional therapies were the most common reasons cited for nonuse. No parent believed that the quality of life of their child deteriorated due to the use of alternative/complementary therapies. CONCLUSION Alternative and complementary therapy use in pediatric oncology patients is common. Factors have been identified that may be associated with undertaking their use.