For the last 25 years human genetics has steadily enlarged its place in internal medicine and especially in psychiatry. Mental hygiene, we believe, may only be efficient when oriented by this discipline. That is the line we follow in our Mental Health Service at the Public Health Clinic of Santana district, São Paulo City. This paper summarizes some data concerning the 300 counselees among 317 ³ seen there from February through July 15, 1952. Even though such data were obtained under close clinical criterion, they have not been statistically evaluated as regards heredobiological aspects: therefore, our conclusions must be taken as provisional. However, some of the recorded findings seem to deserve discussion. Table 1 shows that most frequent conditions met with were: petit mal attacks (32 per cent), irritability (20.6 per cent), headache (20 per cent), atypical epileptic equivalents (12.6 per cent), hyperemotivity (11 per cent); neurosis was diagnosed 15 instances, i.e., in 6.9 per cent of the adults. Relative frequency rates are, however, more illustrative: out of 115 women who had completed at least one pregnancy, 27.8 per cent had miscarried, 13 per cent produced stillbirths, 3.5 per cent suffered eclampsia, 3.5 per cent had surgical delivery. Twin maternities were 11 in number, representing 3.4 per cent of a series of 325 confinements 4, as compared to 1.2 per cent in the average population. Table 2 lists clinical entries for the 84 children of this material, 42 of each sex: night terror, petit mal attacks, seizures, hyperactivity, irritability, were the leading ones. As shown in Tables 3 and 4, for the age range 1-3.5 years (with 22 children), we recorded night terror in 71.5 per cent, hyperactivity in 54.5 per cent, temper tantrums in 54.5 per cent, seizures in 36.3 per cent; and for that of 7-14 years, assembling 39 children, chief disturbances were petit mal (43.5 per cent), irritability (33.3 per cent), headache (30.8 per cent), hyperemotivity (30.8 per cent). The heredological meaning of the above clinical data has helped us in the selection for psychoterapy and home adjustment, as well as to institute the proper medication when needed. A follow-up of 64 children enrolled up to June 1952 disclosed that (1) psychological reorientation was efficient for obstinacy, shyness, maladjustment, enuresis; (2) it was needed to supplement it with medication in temper tantrums, retardation in school, aggressivity; (3) medication alone was enough for petit mal, night terror, panicky reactions, seizures, breathholding spells, sleep disturbances.