Knowledge of pelvic inflammatory disease (PID) epidemiology is essential to the understanding of reproductive morbidity in women. This paper estimates the rate of PID diagnosis in general practice (GP) and the level of association between PID diagnosis and demographic factors. Diagnoses of PID were made at 1.7% of attendances amongst women aged 16 to 46. Increased risk of PID was associated with smoking (P<0.0001), younger age groups (P<0.0001) and lower socioeconomic groups (P<0.0001). Compared to patients who were married, increased risk was also associated with those patients who were widowed, separated or divorced and not cohabiting (adjusted rate ratio (RR)=1.62; confidence limits (CL) 1.35 to 1.97), and with those who were unmarried but cohabiting (adjusted RR=1.32; 95% CL 1.11 to 1.56). General practice is an important focus for the diagnosis and treatment of PID. If intervention and surveillance are to be undertaken effectively, more has to be known about the epidemiology of this important public health problem.