Castilla y León (Spain) is the most extensive region in Europe, with 94147 km(2), and a population of approximately 2.5 million. The programme for the Prevention of Gynaecological Infections and Cancers offers women between 25 and 65 years of age in Castilla y León the possibility to have a cytological test performed every 3 years. The programme was incorporated into the European Network of Cervical Cancer Screening Programmes in 1994. The main results of the 350000 cytological tests performed in the period 1991-1997 are presented.