Background: To date, numerous studies have investigated the epidemiology and clinical characteristics of male pattern hair loss (MPHL). Objective: The purpose of this study was to evaluate a large number of long-term MPHL patients and to compare them to shorter term ones from other studies. Methods: We retrospectively reviewed charts of patients diagnosed with MPHL during a 10-year period at the alopecia clinic at the Department of Dermatology of Myongji Hospital. Results: Among 3,549 alopecia patients who had visited the hospital`s alopecia clinic, 1,360 were patients demonstrating MPHL (38.3%). The most frequent age group was patients in their 20`s (30.1%) followed by those in their 30`s (28.2%), 40`s (17.2%), 50`s (9.9%), and teenagers (8.9%). There were 599 MPHL patients (44.0%) with a paternal familial predisposition, 182 (13.4%) with a maternal familial predisposition, and 118 (8.7%) with familial predisposition on maternal and paternal sides. MPHL was classified based on the Norwood-Hamilton classification: type 2 (20.0%), type 3v (19.4%), and type 3a (16.3%) were the most frequent. Abnormalities in total serum cholesterol were found in 15.1% patients and triglycerides in 36.1% of patients. The most common comorbidity was seborrheic dermatitis, followed by hypertension, hyperlipidemia, diabetes mellitus, and gastrointestinal diseases. Conclusion: This study demonstrated that the period of MPHL diagnosis and treatment becomes earlier in age and milder regarding MPHL type, which may be due to early puberty in teenagers. (Korean J Dermatol 2017;55(7):421 ∼426)