Carpal tunnel syndrome (CTS) has been associated frequently with physical factors and personal factors including smoking, obesity, diabetes mellitus, and hypothyroidism. The purpose of this retrospective case-control study was to evaluate the prevalence of personal factors in patients with CTS compared with a normal control group. The charts of 514 patients who underwent a carpal tunnel release procedure and 100 control subjects were examined for history of smoking, obesity, diabetes, and hypothyroidism. Compared with the control subjects, there were significantly less CTS patients who smoked (p < 0.001; odds ratio, 0.17). However, there were more CTS patients than control subjects who were obese (p = 0.02; odds ratio, 1.77), had diabetes (p = 0.03; odds ratio, 3.02), and had hypothyroidism (p = 0.02; odds ratio, 3.70). These results support previous reports that CTS is multifactorial, with such factors as obesity, hypothyroidism, and diabetes but not smoking to be more prevalent in this group of CTS patients.