Objective: The study aims to assess the frequency of cytological abnormalities in adolescents and young women, to establish the optimum age to start screening. Methods: A retrospective study of cervical cytology results were obtained from the data center at the Santa Casa Hospital of Sao Paulo between January 2006 and December 2014, adopting the Bethesda nomenclature system. The cytology exams were divided into 3 groups: group 1-adolescents (10-19 years old); group 2-young women (20-24 years old); and group 3-adults, comprising the remaining cytology exams. The frequency of cytological abnormalities in the 3 groups was compared using version 3.4.3 of the Epi Info software programand the chi-square statistical test (p < .05). Results: A total of 177,075 satisfactory cytology exams were included in the study. The cytological abnormalities detected in the adolescent group were predominantly low-grade lesions (97.4%); in the young women group, low-grade lesions represented 89.12%, and in the adult group, 76.33%. A significantly greater proportion of high-grade lesions were noted in the adult group, accounting for approximately 24% of all abnormalities detected; in the young women group, it was approximately 11%, and in the adolescent group, it was 2.6%. Conclusions: The natural history of HPV infection shows it is transient in young women, with most cases regressing within 2 years of presentation. Our data confirm that screening of adolescents is not recommended because serious cytological abnormalities and cancer are rare in this group.