Objective: To determine the association between insulin growth factor 1 (IGF-1) and bone mineral density (BMD) in men over 65 years of age. Subjects and Methods: Forty-one male patients aged 65-88 years without a history of drug use or illness which is known to affect BMD were enrolled in the study. The control group consisted of 20 healthy men (19-62 years old). An immunoradiometric assay was used to measure IGF-1 levels. Dual-energy X-ray absorptiometry was used to determine BMD at the proximal femur and lumbar spine. A detailed questionnaire was used to assess the epidemiological findings. Results: The men over 65 years of age had a lower mean IGF-1 level (102.04 +/- 36.65 vs. 196.62 +/- 84.86 ng/ml) and a lower mean BMD at the femoral neck, trochanter and intertrochanteric zones, Ward's triangle and total hip than the controls. No statistically significant association was observed in the BMD of the lumbar vertebrae between the patients and controls. IGF-1 levels were strongly and negatively correlated with age (p < 0.0001, r = -0.82). Logistic regression analysis showed that low IGF-1 levels were strongly associated with osteopenia of the total hip, femoral neck, trochanter and intertrochanteric zone. Conclusion:The finding shows that low serum IGF-1 levels were associated with an increased risk of hip osteopenia and, hence, at least partly responsible for the osteopenia observed in men aged 65 years or over. Copyright (C) 2003 S. Karger AG, Basel.