Background and Design: Although the effects of obesity on the skin are known, there are no adequate studies on this subject. To evaluate obesity-related dermatoses in obese and overweight people and to compare the obtained results with those of individuals with body mass index (BMI) lower than 25 kg/m(2). Material and methods: A total of 500 (mean age: 43.6 +/- 12.8; 318 female, 182 male) volunteer patients aged 18 years and older, who were treated in inpatient clinics except dermatology, and their relatives were included in the study. The subjects were grouped according to BMI: less than 25 kg/m2 (controls, n = 120), 25-29.9 kg/m2 (overweights, n=130), and greater than 30 kg/m(2) (obeses, n=250). The participants were examined dermatologically and all known skin diseases associated with obesity were noted. Results: The total number of dermatoses was statistically higher in obeses and overweights than in controls, as well as in obeses than in overweights. The five most frequently seen dermatoses in all groups were: varicose vein, tinea pedis, striae distensae, acrochordon and onychomycosis, respectively. There were statistically significant differences: between obeses and controls with regard to varicose vein, tinea pedis, striae distensae, acrochordon, onychomycosis, acanthosis nigricans and intertrigo; between overweights and controls with respect to varicose vein, tinea pedis, striae distensae, acrochordon and onychomycosis; between obeses and overweights with regard to striae distensae, acanthosis nigricans and onychomycosis. A positive correlation was detected between BMI and degree of plantar hyperkeratosis in all participants; between BMI and hirsutism score, severity of androgenetic alopecia (AGA) and cellulite in women. Conclusion: While acanthosis nigricans and AGA in females were associated with obesity, the other dermatoses were related with not only with obesity but also with increasing weight gain. (Turkderm 2011; 45: 146-51)