In a practice in an industrial area a cervical cytology service was offered to women, and in the years 1967-70 280 cervical smears were carried out. In 1971 all women born between 1 January 1920 and 31 December 1935 who had not had a cervical smear taken in the preceding four years were sent a letter explaining the service and inviting them to attend. Those who did not attend received a second letter and, if necessary, a visit by a nurse in an effort to persuade them to do so. Eventually 88·4% of the women in this age group who could be traced attended, and 16 abnormal cervical smears were reported. As a result of cone biopsy 12 women were found to have carcinoma in situ.