This document describes a sex education and relationships health project that took place in a public senior high school in Larissa, Greece. Nineteen volunteer students participated in the 25-hour program led by two teachers. Questionnaires were distributed to participants at the beginning, middle, and end to assess needs, attitudes, knowledge of STDs and pregnancy, and evaluate the program. The project aimed to fill gaps in sex education in Greek schools and provide a case study for improving future programs. Implementing and evaluating similar health education programs allows Greek teachers to play an important role in adolescent sexual education.