FIVE MMPI SCALE MEANS WERE COMPARED FOR TWO PAIRS OF GROUPS. THE FIRST GROUP CONSISTED OF FIRST OFFENDERS VERSUS REPEAT OFFENDERS; THE SECOND GROUP, OF SHORT-TERM OFFENDERS (LESS THAN 400 DAYS SERVED) VERSUS LONG-TERM OFFENDERS (900 DAYS OR MORE SERVED.) THE TWO PAIRS OF GROUPS WERE MATCHED FOR SEVERITY OF THE CURRENT SENTENCE BEING SERVED. THE MMPI SCALES UTILIZED TO ASSESS PERSONALITY DEVIANCY INCLUDED THE DEFENSIVENESS (K), DEPRESSION (D), PSYCHOPATHIC DEVIANCY (PD), SCHIZOPHRENIA (SC), AND MANIA (MA) SCALES. MEANS AND STANDARD DEVIATIONS FOR ALL FIVE SCALES FOR BOTH GROUP COMPARISONS ARE PRESENTED IN TABULAR FORM. WITH THE EFFECTS OF AGE, RACE, AND EDUCATION PARTIALLED OUT, THE FIVE SCALE VARIABLES SUCCESSFULLY DIFFERENTIATED FIRST-TIME FELON OFFENDERS FROM RECIDIVIST FELON OFFENDERS. MMPI SCORES FOR REPEATERS WERE SIGNIFICANTLY HIGHER (P GREATER THAN 0.001) OVERALL THAN THOSE FOR FIRST OFFENDERS. AGAIN WITH AGE, EDUCATION, AND RACE EFFECTS CONTROLLED, LONG-TERM OFFENDERS WERE FOUND TO HAVE MORE ELEVATED SCORES OVERALL THAN DID SHORT-TERM OFFENDERS (AGAIN P GREATER THAN 0.001). THE ELEVATED PROFILES OF LONG-TERM OFFENDERS ARE DEFINITELY INDICATIVE OF A GREATER GENERAL PATHOLOGY AND RAISE THE QUESTION OF WHETHER THESE MMPI PROFILES MIGHT BE TO SOME EXTENT THE RESULT OF INCARCERATION. THIS QUESTION WARRANTS FURTHER INVESTIGATION OF THE EFFECTS OF INCARCERATION ON PERSONALITY. A LONGITUDINAL STUDY OF MMPI PROFILES OF INMATES BEGINNING AT TIME OF ADMISSION IS RECOMMENDED. INCLUDED ARE 12 REFERENCES. (JAP)