The purpose of this research is to grasp the spatial environmental needs of a three generation family, thereby to suggest some major concepts which can be used as basic design guidelines for a three generation family housing. Data were collected through a questionnaire survey from 467 housewives living in a three generation family households. Results showed that most respondents want to be seperated from their old parents. This tendency, however, changed once a housing alternative for the three generation living was assumed to have been developed. The most preferred alternative housing units were identified. The desirable proportions of the unit alternatives were 34% for a single unit. 28% for the two connected units. 7% for two separated units within a building and 32% for two separated units in different buildings within the same housing complex.