This questionnaire survey of the parents of elementary schoolchildren in Greece assessed their self-reported knowledge, attitudes and practices towards smoking, diet and exposure to X-radiation. A random sample of 403 household units (379 fathers and 391 mothers) was selected from urban areas of Thessaloniki. Half of the parents who smoked (50.1%) did not ask for permission to smoke from other people and 66.0% regularly smoked in front of their children. On the other hand, 82.6% of smokers recognized the existence of a health risk to children from passive smoking. Parents overestimated the role of nuclear tests and accidents as factors in carcinogenesis. Two-thirds of parents did not know the beneficial role of the Mediterranean diet to health, and dietary intake analysis showed some departure from the traditional Mediterranean diet. A reconsideration of the policy regarding health education programmes concerning cancer prevention in Greece is needed.