Obesity is a risk factor triggering a variety of metabolic diseases. Cynomolgus monkeys (Macaca fascicularis) exhibit spontaneous onset of obesity in adulthood, similar to such onset exhibited by humans. To clarify the characteristics accompanying obesity in female cynomolgus monkeys, we used simple and multiple regression analyses to determine the relationship between body weight and hematological and serum biochemical parameters as well as obesity-related hormones, namely, leptin and insulin. Simple regression analysis showed that body weight was significantly (P < 0.05) correlated with leptin level, insulin level, hemoglobin concentration, hematocrit values, mean corpuscular volume, glucose concentration, and triglyceride concentration. In addition, a multiple regression model containing leptin level, insulin level, mean corpuscular volume, and red blood cell count explained 66.9% of the variance in body weight. Therefore, female cynomolgus monkeys show similar obesity characteristics to humans, i.e., obesity is associated with enhanced synthesis and excretion of leptin in adipocytes, high risk of diabetes mellitus, and high levels of hematocytes. Our results indicate that female cynomolgus monkeys are good models for studying obesity in humans.