Increased urinary excretion of phosphorylethanolamine (P.E.A.) is one of the salient features of hypophosphatasia. This inherited disorder is generally transmitted as an autosomial recessive trait and is characterized by abnormal mineralization of bone, premature loss of deciduous teeth and reduced tissue and serum alkaline phosphatases (A.P.) levels. The authors report a series of patients presenting with pains of skeletal origin attributed to an osteomalacia syndrome on the ground of a bone biopsy. These patients had no history of rickets during childhood but complained of early severe caries of the permanent dentition before the age of twenty. They had neither malabsorption nor renal tubular abnormalities. Their serum 25 OH vitamin D was normal and their serum A.P. levels were within the normal range with a normal isoenzyme distribution. All these patients had increased excretions of urinary P.E.A. and the latter correlate significantly with the degree of osteomalacia. Control patients with a malabsorption syndrome, showing osteomalacia and serum A.P. of the same degree of magnitude as the patients of the first group, have a normal P.E.A. excretion and no correlation appears between the degree of osteomalacia and the P.E.A. excretion. The cases with increased P.E.A. excretion may correspond to adult pseudohypophosphatasia. The signification of increased P.E.A. excretion is discussed.