We attempted to estimate the level of Greek mothers' knowledge relating to the harmful effects of sunlight and whether this knowledge led to protective measures for them and their children. Between September and November 1993, 315 mothers were randomly selected from the outpatient department of our hospital and interviewed by questionnaire about themselves and their children (56% boys, 44% girls, ages 1-12 yrs). Knowledge was estimated by an index score that for 28% of the mothers was considered poor, for 50% moderate, for 16% good, and for only 6% very good or excellent. The score was positively associated with parent education, urban residence, mother's job relevant to the cosmetics industry or the mass media, and history of sunburn in one or both parents. Scores were also established for sunlight-protective measures taken for themselves (28% poor, 45% moderate, 27% just good) and for their children (24% poor, 46% moderate, 30% just good). These scores were significantly associated only with mothers' knowledge of sun protection. Mothers who used sun protection for themselves also applied it to their children. This study shows that mothers in Greece should be encouraged both to increase their knowledge of sun protection and steadily incorporate it into their lifestyle.