OBJECTIVE--The aim was to determine what effect the offer of a cervical smear test when attending for breast screening has on the uptake of cervical and breast screening. DESIGN--The study involved randomisation to compare uptake in those women invited for cervical screening in advance with their breast screening invitation (group 1) with those invited for breast screening only and then offered a smear test upon arrival for breast screening (group 2). The main outcome measure was improvement in the uptake of cervical screening among older women without detriment to the breast screening service. SETTING--The study took place at the Northern Hospital in North Manchester. PARTICIPANTS--Participants were 2131 women aged 50-64 years invited for breast screening at the Northern Hospital in the summer of 1990. MAIN RESULTS--Overall, 54% of the women who were eligible attended for breast screening, 52% attended from group 1 and 55% from group 2. Of those attending for breast screening, 957 were eligible for cervical screening and 193 (20%) had a smear test. There was a difference in the proportion tested from each group (p < 0.001), 28% had a smear test from group 1 and 13% from group 2. Forty five percent of the 193 had not had a cervical smear for at least five years. CONCLUSIONS--The cervical screening facility did attract some women who were overdue for a smear test and who might not normally have attended for cervical screening, and there was no evidence to suggest that it had a detrimental effect on the breast screening uptake. An advanced cervical screening invitation seemed preferable to an invitation upon arrival at the breast screening unit.