While making yearly examinations during the past six years of the boys at a country day school in St. Paul I was early impressed by the relative frequency of cases of undescended testis. The boys ranged in age from 9 to 19 and out of some 260 boys examined in all (the school enrolment averaging about 140) eleven boys showed this developmental defect at some time during this period of observation. The usual method of palpation with invagination of the scrotum, the examining finger reaching the external inguinal ring, failed to locate the missing testis in any of these eleven boys. These were in my opinion cases of undescended testis. The condition was left sided in six cases, right sided in four cases and bilateral in one case. The question was raised whether the parents should be notified of a developmental defect about the existence of which most of the