For the purpose of clarifying to what degree the mothers of developmentally delayed children are involved in treating their child at home. 193 mothers were sampled from 220 mothers of developmentally delayed children below 12 years of age who have visited one of four institutions: the Rehabilitation Hospital of Yonsei Medical Center, Inchon Severance Hospital, Disabled Welfare Center in Myongil-dong, and Nambu Disabled Welfare Hall. The study period was from Mar. 25, 1995 through Apr. 15, 1995. A questionnaire survey was conducted listing the characteristics of the developmentally delayed children, their mothers, mother's satisfaction with their therapists, and the actual conditions of the home treatment. 1. The mothers who treat their child at home for more than 31 minutes a day show a high involvement score, while the mothers of those who give treatment for less than 30 minutes a. day show a low involvement score. That is, the longer the treatment, the greater the involvement score. This indicates a statistically significant result(p<0.01). 2. In cases where a child's father is involved in the home treatment, his/her mother discloses a statistically high involvement score(p<0.001). 3. The result of analysis of cases where other family members, relatives or friends (fathers excepted) reveals a statistically significant high involvement score(p<0.05) for the mother. 4. Mothers in general represent a statistically significant high involvement in home treatment. In the meantime, the mothers in a nuclear family show a higher involvement home treatment than mothers in an extended family(p<0.01). 5. Among those respondents who think that home treatment is helpful and that mothers' involvement in home treatment is helpful, the mothers record a statistically significant high involvement score(p<0.05). When seen from the above perspectives, it seems of much significance that fathers and other relatives or family members play an important role in enhancing the involvement of mothers in home treatment. One point to note here is that providing a long home treatment time is crucial. Therefore, it is recommended that family members have access to rehabilitation treatment for training developmentally delayed children or their care giver; and moreover, we needed to carry out family training or at least arrange for meetings between the family members and medical personnel involved in the child's rehabilitation.