Hyperhidrosis is a disorder of perspiration in excess of the body's physiologic need and significantly impacts one's occupational, physical, emotional, and social life. The purpose of our study was to investigate the characteristics of primary hyperhidrosis in 255 patients at Ajou University Hospital Hyperhidrosis Center from March 2006, to February 2008. Information collected from the medical records was: sex, sites of hyperhidrosis, age at visit, age of onset, aggravating factors, hyperhidrosis disease severity scale (HDSS) rank, family history, occupation, and past treatment. A total of 255 patient records were reviewed; 57.6% were male. Patients with a family history (34.1%) showed a lower age of onset (13.21+/-5.80 yr vs. 16.04+/-9.83 yr in those without family history); 16.5% had previous treatment, most commonly oriental medicine. Palmar and plantar sites were the most commonly affected, and 87.9% of patients felt their sweating was intolerable and always interfered with their daily activities. Our study provides some original information on the Korean primary hyperhidrosis population. Patients who have a family history show signs of disease in early age than those without family history.