Objective: To evaluate the sexual activity behaviors of Turkish adolescents at the transition period from high school to university, a prospective study was conducted inquiring the sexual activity patterns of adolescents applying to different programs of Trakya University in Edirne, Turkey. Material and Methods: All applicants were invited between 2001-2004. There were 16203 participants (3445, 3559, 5402, and 3797, respectively in the years studied) included. Data were analyzed using the Chi Square test. Results: 27.8% of the participants had at least one sexual intercourse (49.2% of the boys and 3.2% of the girls). Sexual activity rate gradually increased between 2001 and 2003, and declined to the 2001 values in 2004 (26.3%, 27.9%, 29.7% and 26.2% respectively). This difference was statistically significant (chi(2): 17.653, p< 0.01). Conclusion: Beginning sexual activity at early adolescence increases the importance some problems including unwanted pregnancies and sexually transmitted diseases. The fact that sexual activity among male adolescents is approximately 15 times more than their girl peers can be attributed to the approach of Turkish culture to sexuality and gender. While augmenting sexual education programs in undergraduate education, this gender difference and cultural factors should be further evaluated in order to reveal possible protective variables for adolescents.