This observational study was conducted on the adolescents referred to a colposcopy clinic in a UK general hospital over a period of 10 years (1996 - 2005). It included 155 newly referred adolescents (age < or = 20 years) with abnormal smear results. The aim of the study was to define the demographic risk factors associated with the development of abnormal cervical smears and identify the incidence of high-grade cervical lesions in this age group. All the risk factors associated with development of HPV infection were found among this group, particularly early age of sexual contact and number of sexual partners. A total of 52.9% of the cases had a smear showing moderate or severe dyskaryosis. The incidence increased to 66.7% among those who had their first sexual contact before the age of 16. Colposcopy and histology confirmed the presence of CIN II and CIN III in 40.6% of cases. The study showed that patients can develop high-grade cervical lesions in their early teens. Delaying the age of onset of cervical screening to 25, as it is currently recommended in UK, will delay the detection and treatment of these cases. A new approach is required to deal with this problem.