Background: During recent decades there have been considerable developments in the field of sexually transmitted diseases (STDs). These changes have been driven largely by the HIV/AIDS epidemic, but also by an increased recognition of the range and severity of complications and sequelae linked to other STDs. Unfortunately, the prevalence and distribution of STDs within the Estonian population are poorly understood. Objective: To assess the acceptability and feasibility of home sampling as a population-based outreach screening program for STDs in a country of post-soviet transitional economy; and to determine the revalence of and risk factors for Chlamydia trachomatis and Neisseria gonorrhoeae infections among the study population. Methods, design: We will perform a cross-sectional study, based on a probability sample, of residents of Tartu County; 1,690 persons (845 women and 845 men) aged 18-39 will be randomly sampled from the Estonian Population Registry. The study activities include an outreach-screening program utilizing home sampling of Chlamydia trachomatis and Neisseria gonorrhoeae, together with a written survey. Those selected from the population registry will receive a mailing consisting of an explanatory letter, a urine sample container, a study survey, and a prepaid return envelope. Participants will be re-screened after 6 months. The main outcome measures will be the response rate and prevalence of infections, as measured by the percentage of specimens testing positive for gonococcal and/or genital chlamydiai infection by polymerase chain reaction. An alternative prevalence estimate will be derived from survey respondents' answers to questions asking whether they have been diagnosed as having gonorrhea or chlamydia in the 12 months prior to the survey. This information will allow us to identify STD infected individuals, and to develop selective screening criteria to be used in general population studies and screening programs in Estonia.