A charitable clinic was set up to provide HIV/STD education and care to commercial sex workers in Ruili. Despite regular promotion of the clinic, few people had utilised the service. Therefore, a qualitative study was carried out among 89 sex workers between March and April 2001 to look at the background of our target group, their medical-seeking behaviours and the range of services expected. The turnover rates of sex workers were high. They had good awareness but poor knowledge of STD/HIV. Many self-medicated or sought advice from peers. They had a serious concern for private practitioners or the quality of drugs from pharmacy stores. They found our clinic inconvenient and did not meet their needs. Subsequently, we refurbished the clinic, implemented changes and retrained our staff. The number of patients treated three weeks after re-opening of the clinic has increased by three folds, with many of them still sex workers, and the clinic's income increased by 58%. Our experience has important implications for policymakers and other NGOs working with sex workers.