289 patients at Port Moresby General Hospital's Sexually Transmitted Diseases (STD) Clinic were interviewed over the January-March 1985 period to evaluate the level of knowledge about STDs shown by people attending the clinic. The questionnaire used included open-ended and precoded questions and had been translated into the 2 major languages spoken in this area of Papua New Guinea. The data were processed by the Prime computer using the BMDP statistical package. There were 231 (80%) males and 58 females; their ages ranged from 15-47 years with a mean of 24.8 and a mode of 20 years. The patients came from all provinces except West Sepik and North Solomons. 85% of the patients had heard about gonorrhea, 38% about syphilis, and 11% about donovanosis. Of those who had heard about gonorrhea, only 25 (10%) knew a corresponding local name for gonorrhea. In general, the patients knew the symptoms of gonorrhea but not of syphilis or donovanosis. A large number responded affirmatively that they had ever suffered with, had sex with someone suffering with, or had sex with someone they suspected of having gonorrhea; a few responded affirmatively to these questions in regard to syphilis and donovanosis. There was considerable variation in the replies to the causes of gonorrhea, syphilis, and donovanosis. The older patients with a mean age of 29.7 years tended to believe the cause was sorcery (puripuri); the younger patients did not. Among the 256 patients that responded to the question about what they considered to be the worst consequences of STD, 39% thought it was death. 66% responded that there was no treatment for STD in their local area; 3 identified the use of leaves, bark of trees, and ashes. The plant most commonly mentioned was the "budowai" plant. The study results indicate that even among those individuals who attend a clinic for STDs the knowledge about the major 3 STDs of the country remains limited. Ignorance of causes, symptoms, and complications is common.