The purpose of this investigation is to see if educable mentally retarded(EMR) boys differ from intellectually normal boys in cardiorespiratory function. Nineteen EMR boys were matched with nineteen normal boys of comparable age. Both groups took the Balke/Ware treadmill test in which the protocol involved maintaining a constant speed of 3.4 mph while increasing the grade from a horizontal degree at the first minute one degree each subsequents minute until the subject reached all out(peak). In analyzing the group test score it was found that the cardiorespiratory function of the EMR group was 20-30 % low (HR p<0.01, VO_2 p