There is a limited amount of empirical data available regarding the cultural and religious variation in perceptions about the age when young people should be regarded as competent to make decisions in health settings. A public survey of 400 adults from diverse religious and ethnic backgrounds was conducted in the UK and Spain. Attitudes were assessed using case vignettes. It was found that high religious practice was associated with recommending a higher age of consent for medical interventions. White British adults were more likely than Spanish adults to agree that younger adolescents should be allowed to consent to medical interventions. The study suggests that there is social, cultural and religious variation in adults' attitudes regarding the age when youngsters should consent to health interventions.