BACKGROUND: Sexually transmitted infections (STIs) remain a major public health problem in Zimbabwe. In Zvishavane, STI increased from 66 per 1,000 in 2002 to 97 per 1,000 in 2005, a 31% increase in cases. OBJECTIVE: To determine the factors associated with contracting sexually transmitted infections (STI) among patients in Zvishavane. METHODS: A frequency matched case control study was conducted. Cases were persons above 15 years diagnosed with STI at three health facilities in Zvishavane urban. Controls were patients who visited the same facilities for other ailments. We interviewed 77 cases and 154 controls. RESULTS: Both cases and controls were knowledgeable about STI. Risk factors for men included sex under the influence of alcohol OR=7.11 (95% CI 2.42-20.85), relationships less than one year, OR= 9.33 (95% CI 3.53-24.70), no condom use at first intercourse OR=5.17 (95% CI 1.64-16.25) and paying for sex OR= 23.65 (95% CI 6.23-89.69). For females the risk factors were non-use of condom at first intercourse OR=2.49 (95% CI 1.02-6.04) and relationships less than one year OR=3.19 (95% CI 1.41-7.23). Significant differences in attitudes were evident among cases and controls. CONCLUSION: Knowledge of STI did not provide protection from STI diagnosis. Limiting the number of partners, consistent condom use, and fidelity are important for both men and women.