OBJECTIVE: To examine the association between country of birth and hospitalization for pelvic inflammatory disease (PID), ectopic pregnancy (EP), endometriosis, and infertility. DESIGN: Follow-up study. SETTING: Sweden. PARTICIPANT(S): A total of 2,170,177 women living in Sweden at some point between 1990 and 2004, categorized into 10 different groups according to country of birth. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Hospitalization for PID, EP, endometriosis, and infertility. RESULTS: For PID and infertility, all groups of foreign-born women exhibited significantly increased risks compared with Swedish-born women. The highest risks of PID were found among women from southern Europe, Eritrea/Ethiopia/Somalia, and other African countries, whereas the highest risks of infertility were found among women from Middle Eastern countries, other Asian countries, and other African countries. Compared with PID and infertility, country of birth was less associated with endometriosis and EP, although some differences were found. All relative risks were adjusted for age, time period, and the women's socioeconomic status. CONCLUSION(S): Even in a country like Sweden, which offers publicly financed treatment for infertility, differences based on country of birth exist. Although data on partners' income were not available to us, it is possible that other factors besides socioeconomic factors are present in the etiology of female health problems related to infertility.