BACKGROUND: The aim of this work was to describe the television (TV) viewing time of preschoolers and to examine factors that may be associated with it. METHODS: A representative sample of 2374 Greek children aged 1-5 years was examined (GENESIS study). Several anthropometric, socio-demographic and lifestyle characteristics were recorded. RESULTS: The mean value of children's TV viewing time was 1.32 h/day. Twenty six percent of participants spent > or =2 h/day in TV viewing. The percentage of children whose TV viewing time was longer than 2 h/day was higher in children aged 3-5 years (32.2%) than in those aged 1-2 years (11.1%). Multiple logistic regression revealed that the time parents spent viewing TV and the region of residence were significantly associated with child's TV viewing time among children aged 3-5 years. Among children aged 1-2 years, the maternal educational status, the region of residence and the maternal TV viewing time were found to be related to child's TV viewing time. CONCLUSIONS: The current findings suggest that almost one third of Greek preschoolers exceed the limit of 2 h/day TV viewing and that parental TV viewing time may be the most important determinant of children's TV viewing time.