Obesity, an important public health issue, is a risk factor for many diseases and has been associated with many genes. The aim of this study was to investigate if there is an association between an NPY gene polymorphism, Leu7Pro, and obesity and/or obesityrelated phenotypes. A total of 84 obese cases (45 female and 39 male) and a total of 77 non-obese control subjects (38 female and 39 male) were included in this case-control study. Body weight and height measurements were used for calculation of Body Mass Index (BMI) and the ones in the ranges of 18 to 25 kg/m 2 were considered normal and the ones 30 kg/m 2 and over were considered obese from the subjects. Minor allele frequency for Leu7Pro polymorphism was 3.5% and it was found to be associated to increased obesity in the population studied. No significant differences were observed between genotype distrubutions and allele frequencies for both obese and non-obese subjects. However, mean BMI values were found to be higher (38,88 ± 2,96) in obese cases having Pro7 allele than non carriers of this allele (35,37 ± 5,16), (p=0.044). This is the first study in a Turkey population which supports the role of Leu7Pro polymorphism in obesity. Further studies with larger sample sizes may