The purposes served by a law enforcement agency's having medical standards are indicated to be (1) ensuring that those hired are capable of fulfilling the required police functions, (2) screening out persons with medical problems that predispose them to frequent sick absences, (3) ensuring that persons hired can function effectively for a reasonable number of years after appointment, and (4) identifying present and past drug users. Data are supplied on medical conditions that have caused the rejection of applicants to the New York City Police Department from August 16, 1979, to February 29, 1980. Steps in the appeal of a medical disqualification and other factors in the attrition process are also discussed. In describing the disability retirement system of the New York City Police Department, it is reported that the authority to determine that an officer is medically unfit to perform full police duty and should therefore be retired is vested in a medical board consisting of three physicians. Data on disabilities warranting retirement are provided for January to June 1981. The instruments used in the psychological screening of police candidates are briefly described, along with the procedure for interpreting them and applying the findings to the hiring decision.