All efforts and economic resources allocated to different means to restore possibilities for women with obligated and damaged fallopian tubes to conceive and of involuntary childless couples to adopt children stress the disability of persons with such sequelae of pelvic inflammatory disease (PID). In contrast, preventive measures have so far obtained much less resources. At present, the number of PID cases in Sweden that become hospitalized has markedly decreased during recent years. This decrease preceded that of the number of diagnosed cases of gonorrhoea but preceded the level off and recent slight decrease of chlamydial cases seen in Sweden. Whether the decrease of PID cases represent a true decrease or not is not known. There has obviously been a shift to a greater proportion of non-gonococcal (chlamydial cases) versus gonococcal PID cases in Sweden. The former type of cases may generally have a milder clinical course which might mean the PID cases nowadays more often are low symptomatic or even asymptomatic and will thereby often be treated in ambulatory practice or not all all. The use of oral contraceptives may protect against ascending infection by chlamydiae, but not against gonococci. This may have a marked influence on the epidemiology of PID in Sweden. There are evidence of chronic tubal chlamydial infection often passing undiagnosed and that the diagnosis is first established in conjunction with ectopic pregnancy or infertility investigation. Ectopic pregnancy as a sequelae of chlamydial salpingitis is on its increase in most countries, including Sweden. The incidence of ectopic pregnancy generally follows more than 5 years after a chlamydial infection.(ABSTRACT TRUNCATED AT 250 WORDS)