Sexually transmitted diseases one of the most serious public health issues in both developed and developing countries. The aim of this study was to evaluate the application of an epidemiological triangle model on prevalent sexually transmitted diseases among married women. Research design: A quasi experimental design was utilized in this study. Setting: This study was conducted at the Obstetrics& Gynecology Outpatient Clinics in Benha University Hospital and Benha Teaching Hospital in Benha City. The sample: Simple random sample of 25% of all women attended to previously mentioned settings which included 150 women. Tools: A structured interviewing questionnaire which includes fourth parts:- a): demographic characteristics b): Medical history of the studied women's regarding obstetric history and present complain c): knowledge about prevalent sexually transmitted disease (chlamydia, gonorrhea, syphilis and trichomoniasis) according to an epidemiological triangle model d): womens' reported practices for prevalent sexually transmitted disease (chlamydia, gonorrhoea, syphilis and trichomoniasis) according to an epidemiological triangle model. Results: 18.0% of the studied women had good total knowledge pre implementation compared with 72.7% post implementation of epidemiological model, and 31.3% of the studied women had satisfactory total practices pre implementation compared with 81.3% post implementation of epidemiological model. Conclusion: The epidemiological triangle model succeeded to improve knowledge and practices of the studied women regarding sexually transmitted diseases Recommendations: Provide continuous educational program to women in Outpatient Obstetrics Clinics to increase knowledge about prevention of sexually transmitted diseases.