This paper presents updated data on bone mineral levels in the proximal femur of US adults, based on the third National Health and Nutrition Examination Survey (NHANES III, 1988–94). The data, collected from 14,646 men and women aged 20 and older using dual-energy X-ray absorptiometry (DXA), include bone mineral density (BMD), bone mineral content (BMC), and area measurements in four regions: femur neck, trochanter, intertrochanteral, and total. The data are provided separately by age and sex for non-Hispanic whites (NHW), non-Hispanic blacks (NHB), and Mexican Americans (MA). NHW in the southern United States had slightly lower BMD levels than those in other regions, but these differences were not significant enough to prevent data pooling. The updated data provide valuable reference values for femur bone mineral levels and have been selected as the reference database for femur standardization efforts by the International Committee on Standards in Bone Measurements. The study also examines potential geographic variations in BMD and assesses the quality of the data, including the impact of nonresponse bias.This paper presents updated data on bone mineral levels in the proximal femur of US adults, based on the third National Health and Nutrition Examination Survey (NHANES III, 1988–94). The data, collected from 14,646 men and women aged 20 and older using dual-energy X-ray absorptiometry (DXA), include bone mineral density (BMD), bone mineral content (BMC), and area measurements in four regions: femur neck, trochanter, intertrochanteral, and total. The data are provided separately by age and sex for non-Hispanic whites (NHW), non-Hispanic blacks (NHB), and Mexican Americans (MA). NHW in the southern United States had slightly lower BMD levels than those in other regions, but these differences were not significant enough to prevent data pooling. The updated data provide valuable reference values for femur bone mineral levels and have been selected as the reference database for femur standardization efforts by the International Committee on Standards in Bone Measurements. The study also examines potential geographic variations in BMD and assesses the quality of the data, including the impact of nonresponse bias.