In an attempt to improve cervical cytology screening uptake in women aged over 40, a mobile screening unit was used to make screening easily available to women at work. This service was organized jointly between the District Health Authority, the Women's National Cancer Control Campaign and the South West Thames Regional Cancer Organization, and was offered to all companies employing at least 25 women. Thirty-nine out of 82 companies accepted the offer. Among those companies which were able to supply a register of their employees aged over 40, 91 per cent of eligible women attended the mobile clinic. The clinic doctors followed District guidelines in not taking smears from women who had been screened and found negative within the previous three years, or who had had a hysterectomy for an unrelated reason. Of the 1038 women who attended the clinic, cervical smears were taken from 568 (55 per cent). Fifteen women were found to have cervical neoplasia, of whom nine had either never been screened before or had last been screened more than five years previously; a further two women (one of whom was found to have early invasive cancer) had previously had an abnormal smear for which the recommended follow-up had not been done. It was not possible to quantify the benefits of other tests (clinical breast examination, blood pressure, urinalysis and gynaecological examination) included in the screening clinic, but they were popular with the women attending. Provided that the health authority is involved in the planning and organization of workplace screening, it can be a valuable adjunct to improving screening coverage, particularly for women aged over 40.