Bone mineral content (BMC) in the radius of 23 osteogenesis imperfecta (OI) patients (1-26 yr) was measured with SPA technique. Comparing the values of OI type I. patients with that of type III. patients, the decrease of BMC was more prominent in the latter group, however, the two group hadn't been distinct from each other at p < 0.05 level. Based on the measurements of 39 relatives (mother, father, brother) the method seems not to be helpful in screening of gene-carrying relatives because of the high variability of the phenotype of the disease. Follow-up SPA studies-avoiding the repositioning errors-inform about the therapeutic effect.