30 female patients with anorexia nervosa (AN) were studied and compared with 45 age-matched normal controls. All the patients had severe weight loss and nutritional involvement. Mean and SE body mass index, BMI (kg/m2) were 15.8 +/- 1.8 in anorectics compared to 21.7 +/- 4.7 in normals (p < 0.0001). All the patients presented amenorrhea lasting between 3 and 120 months (mean 24.8 +/- 25.3). A nutritional survey and a dual photon bone densitometry, including spine, hip, total body and total mineral content were performed. The mean values +/- SE in patients and controls were: spine densities (L2-L4) in g/cm2: AN 0.84 +/- 0.1, controls 1.03 +/- 0.1 (p < 0.002). Total mineral content (g): AN mean 1733 +/- 261, controls 2045 +/- 276 (p < 0.0001). In anorectic patients the correlations between bone density and BMI for spine were r: 0.52 (p = 0.002), for hip r: 0.37 (p = 0.04), and total mineral content vs BMI gave r: 0.64 (p = 0.0001). Mean calcium intake in 23 studied patients was lesser than the classic recommended dietary allowance in the whole group, it was less in the pure restricters as compared to vomiters. The relation between duration of amenorrhea and bone density showed than a decrease in the later was evident when the absence of menses was longer than 24 months. In conclusion, in patients with AN there is a real decrease in bone density which is strongly related to low weight and in lesser proportion to the duration of amenorrhea, particularly when it was longer than 24 month.