Nineteen men who had suffered permanent paraplegia a median of 4 years previously were studied. Eight also had varying degrees of neurological deficit of the upper extremities. Bone mineral, biochemical and hormonal values were compared to those in an age-matched control group in order to detect evidence of systemic osteopenia. There were very considerable individual variations in bone mineral density (BMD) deficits among patients compared to controls, probably partly due to methodological problems. Significant BMD deficits were found in the metaphysis (45%) and diaphysis (26%) of the tibia, while the deficit of the distal forearm was barely significant for the group as a whole. There was a negative correlation between time since injury and degree of BMD deficit in the lower extremity. Those with neurological affection of the upper extremities had a greater BMD deficit of their arms than those with neurologically intact arms. It was concluded that osteopenia in paraplegics is largely confined to the paralysed extremities, and thus not systemic. Serum alanine aminotransferase, phosphate, follicle stimulating hormone, and free androgen index (testosterone/sex hormone binding globulin) were mainly within normal limits, but significantly higher in paraplegics than in controls. Osteopenia in these patients is thus not due to gonadal dysfunction.