This paper aims to complement existing clinical guidelines by providing evidence of the relative cost-effectiveness of treatments for infertility in the UK. A series of decision-analytical models have been developed to reflect current diagnostic and treatment pathways for the five main causes of infertility. Data to populate the models are derived from a systematic review and routine National Health Service activity data, and are augmented with expert opinion. Costs are derived from an analysis of extra-contractual referral tariffs and private sector data. Sensitivity analysis has been carried out to take account of the uncertainty of model parameters and to allow results to be interpreted in the light of local circumstances. Results of the modelling exercise suggest in-vitro fertilization is the most cost-effective treatment option for severe tubal factors and endometriosis, with surgery the most cost-effective in the case of mild or moderate disease. Ovulatory factors should be treated medically with the addition of laparoscopic ovarian diathermy in the presence of polycystic ovarian syndrome. For other causes, stimulated intrauterine insemination (unexplained and moderate male factor) and stimulated donor intrauterine insemination (severe male) are cost-effective.