To determine whether a cervical screening call system based in general practice in a deprived inner city area would increase the numbers of women who came forward for cervical smears the response to letters of invitation for screening was monitored for one year in one general practice in the Paddington and North Kensington district of London. Women aged 20-64 were identified from the computerised age-sex register. Only 16% of these women had had a smear test. A total of 750 cali letters was sent out. Initially the response was poor (57 women; 22%), and 85 (32%) letters were returned marked "address unknown." After the age-sex register was updated the response to call was 330 women (44%). The response of women aged over 35 was better than the response of women aged 35 and under (229 (53%) v 101 (32%)). In the year of the study the number of women aged 20-64 on the revised register who had been screened rose by 330 (14%).A general practice based call system can improve uptake of cervical screening even in a highly mobile, socially underprivileged population.