Breast screening in the Herault Department (France) has been carried out since July 1990. As with other French programmes, it is a population-based screen, whose main features are related to its organization in that: (a) it is performed by a specific unit (the 'Institut Montpelliérain d'Imagerie Medico-Biologique'); and (b) the group of women targeted is those aged 40-70 years. The two-view mammography is performed every 2 years in mobile units. This paper presents the results after 30 months: 26,026 participants were screened from a target population of 52,617 women, giving a participation rate of 49%. The recall rate and the biopsy rate observed were 7% and 1.5%, respectively. The predictive positive value was 8.4% for a positive test while it was 35% for the biopsy; the values increased with age. 137 cancers were observed giving a detection rate of 5.3%, of which 82% were in situ. Small (< or = to 10 mm) tumours represented 41.5%, and 71.5% of the cancers were node negative. The surgical treatment was conservative for 66% of them.