Objectives: The objectives of this study were to determine whether periodic presumptive treatment (PPT) for sexually transmitted infections (STI) in service women could be implemented in 3 border provinces of Laos and whether its implementation was associated with a reduction in the prevalence of cervical infections. Study Design: Four hundred forty-two service women were interviewed using a standardized questionnaire in 3 border provinces at baseline (day 1) and 419 3 months (day 90) later. Azithromycin at a dosage of 1 g was administered at monthly intervals over 3 months in Khammouane province, on days 1, 30, and 90 in Oudomxai and days 1, 60, and 90 in Savarmakhet. Urine samples were collected at baseline and day 90 for gonorrhea and chlamydia testing. Results: Baseline samples showed very high levels of both gonorrhea and/or chlamydia of 42.7% in Oudomxai, 39.9% in Khammouane, and 22.7% in Savannakhet. At day 90, after 2 or 3 rounds of PPT, these were, respectively, 12.3%, 21.9%, and 17.0%. Overall, the prevalence of any cervical infection decreased by 45% from 32.4% (95% confidence interval [CI] = 28.1-36.9) at day 1 to 18.0% (95% CI = 14.5-22.1) at day 90 (P < 0.001). Conclusions: Lower prevalences of cervical infections were observed after 2 to 3 rounds of PPT. The optimal time between rounds of PPT is uncertain, but while these high STI rates prevail, a 1- to 2-month gap is recommended. After the introduction of this PPT project, costs of STI drugs reduced 5-fold making PPT a sustainable intervention in Laos for service women until user-friendly services are developed.