Recently acquired knowledge about vitamin D metabolism has improved our understanding in different varieties of osteomalacia. Many new causes of osteomalacia continue to be found. Radiologic and biochemical changes are not always characteristic and may occasionally be misleading. Bone biopsy after a double tetracycline label is helpful in differentiating osteomalacia from high bone turnover conditions and is recommended in most patients with a generalized rarefying skeletal disorder. Even if the underlying disease state cannot be corrected, effective therapy is available in most varieties of osteomalacia. The newer metabolites of vitamin D should soon be generally available to the medical profession. Their use will make treatment of osteomalacia more individualized and specific.