We examined health-care seeking practices among patients with sexually transmitted diseases (STDs) in south China. In 1995, we recruited a consecutive sample of 939 STD patients attending the STD clinics of the Municipal STD Control Centers of Guangzhou and Shenzhen, 'special economic zones' near Hong Kong. Attending physicians interviewed patients face-to-face using a standard survey questionnaire. Twenty-seven per cent of all subjects had sought treatment elsewhere for their presenting complaints, before visiting a study clinic. The main sources of prior treatment were private physicians followed by public clinics and drugstores. Women were more likely than men to delay in presenting their current symptoms to a study clinic (32% vs 25%, P=0.046). Factors associated with treatment delay differed by gender. Among men, seeking prior treatment from private physicians (OR=3.31; 95% CI=1.70, 6.43), having no urethral discharge (OR=4.00; 95% CI=2.33, 6.85), having engaged in sex trade (OR=1.64; 95% CI=1.03, 2.63), or being a resident in Shenzhen (OR=1.80; 95% CI=1.12, 2.89) were more likely to delay seeking treatment. Among women, only living in Shenzhen (OR=2.86; 95% CI=1.56, 5.25) was associated with treatment delay. Promotion of appropriate health-seeking behaviours and better management of STDs must be a top priority to slow a rapid spread of STD/HIV in China. Health education, improvement of STD care in the public and private sectors, and regulations of unauthorized private physicians, may help with STD control and HIV prevention.