Objective: To identify sexual risk behaviours associated with lifetime risk of urethritis in prison inmates.Design: A cross-sectional study using a pre-designed questionnaire.SETTING: Fourteen prisons throughout the Sindh Province, Pakistan.SUBJECTS: Three thousand three hundred ninety-five prison inmates incarcerated during July, 1994.MAIN OUTCOME MEASURE: Lifetime risk of urethritis occurrence (whether or not the subject was ever affected with urethritis up to his present age)Results: Lifetime risk of urethritis occurrence in the study population was 20.8% (706/3395). The final multivariate logistic regression model indicated that risk behaviours associated with lifetime risk of urethritis in this population were \u27sexual intercourse with a female\u27 (adjusted OR = 2.18; 95% CI 1.60, 2.95), \u27multiple female sexual partners\u27 (adjusted OR = 1.67; 95% CI 1.28, 2.18) and \u27sexual intercourse with man\u27 (adjusted OR = 2.75; 95% CI 2.29, 3.31).CONCLUSION: The prevalence of urethritis in this population was very high. High prevalence of various risky sexual behaviours among inmates indicates, their unawareness as to what precautions they might take to avoid risk of acquiring STDs including HIV. The study subjects meet the characteristics of a core group of STDs transmitters and provides short window of opportunity for STD/HIV control programs to intervene, while they are in detention to reduce the risk not only for this group but also for general population