Objective: To compare the efficacy and cost-effectiveness of two reminding strategies addressed to women who did not respond to a first invitation to undergo cervical cancer screening. Study Design: A randomized study was carried out by a programme created in Alsace to organize cervical cancer screening. In total, 10,662 women who did not have a smear test 1 year after a first notice was sent, were randomly allocated to receive either a new letter with a reply coupon or a telephone call. The uptake of screening was measured using routine data. Efficacy and direct costs of the two methods were compared. Results: Uptake at 8 months was 6.3% [95% confidence interval (CI) 5.6–7.0%] for telephone calls and 5.8% (95% CI 5.2–6.4%) for letters. The difference was not significant. More information was collected through telephone calls than by letters, but with less reliability. Furthermore, telephone calls were more costly. Conclusions: We found that in our region, a mail reminder was as effective as, and less expensive than, a telephone call; moreover, it was applicable to the whole population, including patients without a telephone.