Prenatal classes have been held for expecting mothers at Health Centers in Yokohama city to give guidance on nutrition. As this class is held in every Health Center in the city, it is quite well known; however, there is only limited volume of practical data for the dietary habits of prenatal mothers and their awareness on nutrition. The authors from 9 Health Centers of Yokohama city investigated the food ingestion, preferences and the awareness for nutrition of prenatal mothers who attended the classes. The survey was conducted twice; i. e. once (400 respondents) during the class and once after delivery (263 respondents). The method consisted of a questionnaire on their awareness and a record taking of their meals (3 days). The result is shown below: 1) 45.3% of respcndents experienced changes in preference for foods, but 83.4% of them returned to old habits after delivery. As is widely known, the pregnant women began to prefer sour or rich dishes. 2) Although 97.3% of respondents took good care of their diet, the percentage dropped to 48.3% after delivery. 3) The dietary patterns of the respondents can be classified into that of mainly rice and that of mainly bread. Those who mainly eat rice took better balanced diet than the other group. In other words, the first group was better than the second group in selection of foods from 6 basic food groups. 4) Respondents took between-meal snacks more frequently than after delivery. As such snacks amount to a greater importance from nutritious point of view, the prenatal class should place more emphasis on improving the quality of such snacks.