Background: The objective of this study was to assess bone mineral density (BMD) of the lumbar spine and the proximal femur in male and female athletes performing different high level sports, in unspecifically trained sport students and in untrained subjects. Methods: BMD of lumbar spine and proximal femur were measured by dual-energy-x-ray-absorptiometry in 209 female and 173 male subjects aged 17-30 years (37 runners (R), 16 cyclists (C), 22 triathletes (TRI), 62 team sport athletes (TS), 45 combat/power athletes (P), 13 ballet dancers (BL), 126 sport students, 61 untrained controls (UT)). Results: Highest BMD values were found in P and TS. Lowest values were found in UT, BL, and endurance trained athletes (R/C/TRI). Conclusions: BMD is probably dependent on the specific mechanical demands of different sports.