Introduction and objectives: The aim of the study is to evaluate the prevalence of andrological abnormalities, such as phimosis and foreskin sliding abnormalities among male adolescents, and if these might interfere with sexuality, leading to a later onset of sexual experiences. Material and methods: Between April and May 2015 a prevention campaign in andrology was conducted in an area surrounding Rome, Ostia and the Ladispoli area, among 15-19 year-old students. The screening consisted of a frontal lesson with the students in order to explain and raise the awareness of the most common andrological abnormalities and diseases. Among the routine anamnestic questions, three additional questions were submitted to 18-year-old boys: “Have you ever had sexual intercourse?”, “How old were you when you had your first sexual intercourse?” and “Have you consulted a health professional about your genitals?” Finally a detailed clinical examination was performed and the outcome sent to the family and to the General Practitioner (GP). Results: A total of 552 high school students were evaluated. Out of them 131 (23.7%) were at least 18 years old. Among these, 79 (60.3%) said that they had already had full sexual intercourse. The phimosis and foreskin sliding abnormalities had a prevalence of 12.9% within the 18-year-old students, with a significant prevalence among those who hadn’t had any sexual intercourse at all, 21.1% vs 7.5% p = 0.023. The age of the complete first sexual experience in the circumcised young men was the same as those without phimosis; 89% of the boys with phimosis hadn't had an andrological examination in the previous years. Conclusions: Male adolescents with phimosis or preputial sliding abnormalities tend to have a late onset of sexual experiences compared to same aged boys without phimosis. These data support the urgent need of an andrological consultation for all boys at the beginning of, and during, their adolescent period because genital abnormalities may interfere with sexuality. Finally, in order not to confuse effects with causes, we suggest matching a routine genital physical examination in all studies dealing with sexual psychological aspects of male adolescents.