To study the understanding, attitudes and practice of primary care doctors in the prescription of hormonal post-coitus interception, along with the social and demographic, educational, legal and ethical variables associated with this prescription.Cross-sectional descriptive study.Area IV de INSALUD in Asturias.Family doctors, excluding locums (n = 178).An anonymous self-administered questionnaire with 33 questions, re-sent once, between November 1999 and February 2000. The association-independence of variables was contrasted through the chi 2 test (a statistically significant association if p < 0.05). 77% responded, 51% of whom were men. Average age was 43 (SD = 6.69), with professional experience of 17 years worked (SD = 6.87). 47% were family doctors and 39% general practitioners. 85% worked in health centres; 46% in urban settings. 71% were catholics, 73% (95% CI: 66%-80%) had been asked on at least one occasion in the previous six months for the post-coitus pill (PCP), with demand greater in the urban environment (83%). 18% considered the PCP an abortion method. 88% said they would prescribe it (95% CI: 82.5%-93.5%), of which 30% (95% CI: 16%-44%) did so according to WHO recommendations. 100% of the "non-prescribers" were catholics.Most doctors receive requests for the PCP and prescribe it on demand, though prescription varies with age, categories and, in particular, religious belief. Only a third prescribes according to WHO recommendations.