The purpose of this study was to investigate the association of the Singh index, cortical thickness index (CTI) and calcar-to-canal (CC) ratio with bone mineral density (BMD) as well as their relationship with physical parameters [age, gender, height, and body mass index (BMI)] in order to assess their potential as an indirect indicator of osteoporosis. BMD, Singh index, CTI and CC ratio as well as the physical parameters were obtained from hip radiographs and clinical records of 140 Korean adults. Linear relationships between the areal BMD of the femoral neck and the parameters as well as between each parameter were obtained. To determine the association between BMD and the radiological parameters, multiple regression analyses were performed after adjusting for the four physical parameters. The CTI was positively associated with BMD (p = 0.040), whereas the Singh index (p = 0.209) and CC ratio (p = 0.655) were not. The CTI was negatively associated with age (p = 0.02) and positively associated with height (p = 0.0001) and BMI (p = 0.001). The CC ratio was also positively associated with age (p = 0.0001) and negatively associated with height (p = 0.033). In conclusion, of three parameters available from plain radiograph (age, height, BMI), only CTI was significantly associated with BMD. CTI can provide a tool for rapid assessment of osteoporosis from plain hip radiographs.