The normal value of the serum. Alkaline phosphatase varies by the methods used, and maximum normal value by the Bodansky modification method is known to be 10 Bodansky units in adult and 20 units in child. The author calculated serum alkline phosphatase value of various types of otitis media patients, (10 male acute otitis media, 10 male chronic catarrhal otitis media and 30 male chronic suppurative otitis media and its complication with pseudocholesteatoma) according to Bodansky modification method and at the same time calculated 20 normal control group, comparing with each other, and following results were obtained. 1) In the majority of acute otitis media, the alkaline phosphatase value fluctuated slightly from normal level. 2) Most cases of chronic otitis media showed increase in serum alkaline phosphatase value except the cases that clinical pathology is localized in tympanic mucous membrane. In the case pathologically changed progressively, such as caries, granulation and cholesteatoma, significant increase in alkaline phosphatase value was observed. 3) The catarrhal otitis media cases remained in almost normal value except 2 cases that marked pathological changes were observed in drum membrane.