OBJECTIVES: To compare mobile phone messaging and postal reminders as means of increasing the attendance rate during the first 24 weeks of lipid-lowering therapy among hyperlipidemic patients in primary care. METHODS: The study was a randomized controlled trial of 918 patients from 19 family practice clinics conducted between February 2003 and June 2005. Patients were randomly assigned to receive mobile phone message reminders, postal reminders, and control strategies. To ascertain attendance rates, patients were regularly followed up 12 to 24 weeks after their treatment. Reminders were sent on average at 16 weeks. The primary measure was the attendance rate at 24 weeks. A secondary outcome was identifying the direct cost and benefits of each reminder type. RESULTS: Overall attendance rate was 74.1%. This differed between groups, with 76.1% attendance for the mobile phone messaging group, 73.5% for postal reminders, and 72.4% for the control group. According to a multivariate analysis, the mobile phone messaging group had a significantly higher attendance rate (OR 1.48, 95% CI: 1.01-2.16) than the control group, but the postal reminder group (OR 1.15, 95% CI: 0.79-1.69) did not. Moreover, for one additional visit, the marginal cost of mobile phone messaging (USD 3.1) was much lower than that of postal reminders (USD 47.0). CONCLUSION: Mobile phone messaging is a more cost-effective method to increase the attendance rate at 24 weeks after lipid lowering therapy among hyperlipidemic patients.