Hideo Nakayama was the Chief Dermatologist in Tokyo Saiseikai Central Hospital from 1970 to 1995. He was the Visiting Lecturer of Keio University, School of Medicine, from 1973 to 1995, Chief Dermatologist and Allergologist at Nakayama Dermatology Clinic from 1995 to 2015. He has graduated from Keio University, School of Medicine in 1961. Currently, he is the Advisor Doctor in Meguro Chen Dermatology Clinic (Tokyo). He has discovered new allergens, such as palladium,benzyl salicylate, R-219 (D&C R-31), ylang-ylang oil, ?-acaridial, etc., and developed new treatment systems by allergen control with pigmented cosmetic dermatitis, textile dermatitis, dental metal allergy and atopic dermatitis