A study of invasive cervical cancer in Southampton and South West Hampshire is reported, covering three consecutive three year periods during which the screening coverage increased from an estimated 60% to a recorded 87% of eligible women aged 20-64. From the first to the third periods of the study in that age group registrations of fully invasive squamous cell carcinoma (stage lb and above) fell from 64 to 30 (53%), which was largely counteracted by an increase in microinvasive squamous cell carcinoma (linear trend: P<0.0001). In the same age group registrations of adenocarcinoma rose slightly, which resulted from an increase in the number diagnosed at a depth of invasion of less than 3 mm. There were no significant changes in the numbers of stage III and IV cancers or among cancers in women aged 65 and over. A strong inverse association was found between stage of both histological types of cancer and their likelihood of being screen detected rather than symptomatic: 91% of screen detected cancers were diagnosed at stage I compared with 38% of symptomatic cancers. There was a slight downward trend in the incidence of cancer per 100,000 total female population across the three periods of the study with a significant trend towards low stage disease, which is likely to reduce mortality in years to come. The trend towards screen detected cancers and cancers of less than 3 mm depth of invasion is presented as a positive outcome to be expected in early rounds of increasing the screening coverage.