PURPOSE: Sildenafil citrate(Viagra(R)), a PDE-5 inhibitor in the corpus carvenosum to facilitate penile erection has improved impaired erectile responses in men and has been accepted as a primary treatment of erectile dysfunction. However, complications occurred by Viagra have increased due to its overuse and misuse. Therefore, we have performed a survey to compare physicians and general population in Busan, Korea to assess their understanding of Viagra. Methods and Materials: In 2007, printed surveys were mailed to randomly sampled candidates of 197 primary physicians and 696 individuals from general population, 327 medical students in Busan were surveyed by door-to-door visits. We assessed opinions associated with Viagra eliciting their understanding about its safety, direction, and complications. Data were analyzed using SPSS and were identified by crosstabulation analysis using Ki-square test. RESULTS: Of 1,265 eligible responses, several differences were found between the 3 groups. Compared to general population, the others were more likely to understand the efficacy, directions, and complications of Viagra. Physicians and medical students(43.1% and 39.0%) gave more preference than general population(26.1%) to using Viagra. There were differences in understanding of Viagra with changes of education level. However, it showed no significant differences about idea of illegal Viagra and combination usage with nitrates. Conclusion: The number of patients using Viagra is increasing but their understanding about Viagra is still poor. Moreover, general populations understand Viagra as 'assistant' for erection poorly. Even some medical students understand more than physicians. The ideas of complications would likely affect to negative thinking about usage for Viagra. Therefore more active and continuous educations for proper use of Viagra are suggested for medical efficacy and less complications.