The psychological characteristics of 36 adult hemophiliacs, mean age 29.1 years, were analyzed by means of the Minnesota Multiphasic Personality Inventory (MMPI).The MMPI profile patterns were compared between various groups of the hemophiliac sample. By the clinical criterion used in our clinic, the sample was divided into severe and mild-moderate groups. The mild-moderate group appeared to be mildly anxious-hysterical, frightened, and health preoccupied with a profile of '317-2 9 5684 0/. The severe group appeared to be more estranged and alienated than the mild-moderate group, and has a significantly higher psychopathic deviate scale (P<.01). The mean profile of the severe group was '458 23-9167 0/.The most striking differences were found in comparing subgroups of high (N=9) vs low bleeders (N=9) within the group of severe hemophiliacs with factor levels of 3% or less. The high bleeders (>243 units/lb/year, mean Factor VIII level 1.6%) were much more disturbed, had all mean clinical scales above 60 (8'25137496-0/) and significantly higher scores for Depression, Psychasthenia, and Schizophrenia (P <.05). The low bleeders (< 243 units/lb/year, mean Factor VIII level 1.8%) had no mean scale scores above 60 ('34519687 2/0).The results indicated a clear difference in the psychological adjustment of the high and low bleeders to their illness. The high bleeders had a marked increase in self negativity i.e. a sense of being defective, of hopelessness and of pessimism. Surprisingly, the low bleeders has adjusted auite well to their serious vulnerability.