The province of Bali with the largest number of foreign tourists to the 9.73% growth in 2011,became the public and government concern in the case of HIV/AIDS. Denpasar city was ranked to be thefirst of people with HIV by 1,949 people (KPA province of Bali, 2012). The study on the sex tourism inASEAN is reported by the Child Wise Tourism Australia in 2007, Indonesia was considered as thedestination for sex tourism which involve children and young women. The aim of the study was toanalyze the effect of group therapy self-protection knowledge and attitudes of Commercial street sexworkers aged 15–18 years. Method: The design used in this study was pre - experimental design with thedesign of One Group Pre- test - post-test design. The sample of this study was 18 people consisting of 3groups, each group consisting of 6 persons. Snowball sampling technique was used to the respondentswho met the inclusion criteria. Result: Statistical test results using paired t - test sample showed anincrease in knowledge on STI, attitudes of self-protection. Knowledge t = 7243 , the attitude of t = 6,803with table=2:21. Discussion: The conclusion of this research showed that there were significant effect ofthe interpersonal group therapy model with knowledge of STI, attitudes of self-protection against STI tothe customer. It was suggested that socialization and coaching on the use of condoms should be increasedas well as providing sustainable skills in order to become capital for them not to go back intoprostitution.