Sexually active adolescents are at high risk for unintended pregnancy and sexually transmitted diseases. We identified a cohort of 6089 women aged 13 to 21 years who in 1985 either delivered an infant at Parkland Hospital (3154) or used the outpatient clinics (2935). We reviewed those records and others in the Dallas County sexually transmitted disease (STD) clinic for the period 1983 through 1988 to determine the prevalence of visits to the Dallas County STD clinic by pregnant and nonpregnant adolescents, STD diagnoses at initial visit, whether STD visits and diagnoses varied by pregnancy status or ethnic background, and how the women were referred to the STD clinic. Similar percentages of nonpregnant (13%) and pregnant (11%) women had an STD visit, and most adolescents who visited the STD clinic had an STD diagnosis made. Gonorrhea and syphilis were the STDs diagnosed most frequently in both pregnant and nonpregnant adolescents. Regardless of pregnancy status, black adolescents were 7.3 times more likely to have an STD visit. Referral by a sexual partner was the second most common reason that adolescents sought STD care. Our study provides only minimal estimates of STDs among adolescents but indicates STDs, regardless of pregnancy status, are a more common medical problem than has been reported previously. Referral by sexual partners may be an important way to reach adolescents at risk for STDs.