BACKGROUND: Australian guidelines allow women to cease having Papanicolaou (Pap) tests at the age of 70, providing they have had two negative smears in the previous 5 years. In Victoria, a standard reminder letter system is in place and women receive one reminder letter 27 months after their last Pap test. METHODS: A targeted letter informed by qualitative research was developed to specifically encourage older women to have a final Pap test. The Victorian Cervical Cytology Registry (VCCR) was used to identify 15,000 women aged 65-69 who had not had a Pap test for at least 3 years and up to 17 years. Women were randomly allocated to receive either no letter (control group), the targeted letter or a personally addressed general reminder letter. RESULTS: At 11 weeks follow-up, 4.3% of women (CI 3.7-4.8%) who received the targeted letter had attended for a Pap test compared with 4.7% (CI 4.1-5.3%) of those receiving the general letter and 1.6% (CI 1.2-1.9%) of the control group. Effectiveness was limited to women whose test was no more than 10 years overdue, and was particularly strong for those whose test was 3-5 years overdue. CONCLUSIONS: This suggests that a reminder letter was effective, but that targeting the information in the letter did not further improve screening attendance. A second reminder letter sent to women before their Pap test is more than 5 years overdue has potential for increasing the number of women attending for screening.