Three cases of connective tissue tumors causing hypophosphatemic osteomalacia are reported and the literature is reviewed. In two of our patients the tumors were completely excised with total disappearance of the symptoms. In one case a total excision was not possible and the symptoms of this patient have not completely disappeared. The substance responsible for the syndrome has not been identified yet, but probably interferes with vitamin D renal hydroxylation, thus causing osteomalacia. As more than 30 per cent of cases of this condition have been reported in the last 5 years, it is suggested that these tumors are more frequent than previously believed.