THE CURRENT WORK RELIES SOLELY ON THE RECORDS PROVIDED BY THE NEW YORK STATE DEPARTMENT OF MENTAL HYGIENE. ANALYSIS OF THE RECORDS SHOWED A MARKED INCREASE IN THE NUMBER ON INSANITY ACQUITTALS IN NEW YORK OVER THE PAST 12 YEARS. ALTHOUGH THE VOLUME HAS INCREASED, THE CHARACTERISTICS OF THE ACQUITTED DEFENDANTS HAVE CHANGED LITTLE, AS HAVE THE OFFENSES FOR WHICH THEY WERE ACQUITTED. ACQUITTEES ARE OLDER AND MORE OFTEN WHITE AND FEMALE THAN ARE PRISON INMATES. MURDER IS THE MOST FREQUENT OFFENSE FOR WHICH BOTH MEN AND WOMEN ARE ACQUITTED BY REASON OF INSANITY, WITH A SUBSTANTIALLY HIGHER FREQUENCY OF MURDER CHARGES AMONG ACQUITTED WOMEN. LENGTHS OF HOSPITALIZATIONS VARY WIDELY, BUT LONGER DETENTION IS ASSOCIATED WITH THE MORE SERIOUS OFFENSES SUCH AS RAPE. OF THE DEFENDANTS ACQUITTED FROM 1965 THROUGH 1976, 40 PERCENT REMAINED HOSPITALIZED FOR AN AVERAGE OF 1,701 DAYS, AND 89 PERCENT OF THOSE ACQUITTED IN THE PAST 2 YEARS WERE STILL HOSPITALIZED AS OF JUNE 1978. THE SUCCESSFUL USE OF THE INSANITY PLEA DOES NOT OCCUR EVENLY ACROSS THE STATE. PHYSICIANS, LAWYERS, COURTS, AND THE MEDIA SHOULD REQUIRE STATES TO COMPILE DATA NEEDED TO DESIGN A RATIONAL SOCIAL POLICY REGARDING THIS ISSUE. REFERENCES AND TABLES ARE PROVIDED. (AUTHOR ABSTRACT MODIFIED--LWM).