Lichen sclerosus et atrophicus is a chronic inflammatory sclerotic and atrophic disease of unknown cause that predominantly affects male and female genital skin. This study was designed to evaluate histological characteristics of congenital and acquired phimoses among pediatric (n=60) and adult (n=60) male patients who were admitted for circumcision to the Clinics of Urology and Pediatric Surgery of Kaunas University of Medicine Hospital between 2000 and 2003 and to determine the rate of lichen sclerosus et atrophicus and other histological diagnoses among them. This study demonstrates that 45.1% of congenital and 62.3% of acquired phimoses show histological signs of lichen sclerosus et atrophicus. The rate of lichen sclerosus et atrophicus was statistically significantly higher among patients with acquired than congenital phimosis. Boys with acquired narrowing of prepuce were statistically significantly 3.9 times more likely to develop lichen sclerosus et atrophicus than those with congenital phimosis. There were no statistically significant differences between rates of lichen sclerosus et atrophicus and other dermatological diagnoses among pediatric and adult male patients if the type of phimosis (acquired or congenital) was considered. Histological features of lichen sclerosus et atrophicus and other histological diagnoses in boys and men with phimosis were detected with equal frequency irrespective the age of the subjects. The rate of lichen sclerosus et atrophicus was similar among all boys (56.7%) and men (53.3%) treated for phimosis. Only the type of phimosis had a statistically significant influence on the rate of lichen sclerosus et atrophicus and other histological diagnoses.