The authors present socio-hygienic characteristics of 1137 adolescents from 68 boarding homes for mentally-retarded children and clinical characteristics of 102 of these adolescents. The latter type of characterization includes the description of the degree of imbecility and attendant psychopathological disturbances. On the basis of the developed model of rehabilitation (organization of differential rehabilitation regimens, individual programme of communal and occupational adaptation of mentally retarded children, the organization of their training to acquire professional skills in specially created conditions of an industrial enterprise) the authors show a positive dynamics of attendant psychopathological disorders. It has been established that a certain proportion of adolescents with marked mental retardation may acquire professional skills and actively participate in socially useful production.