RIM, Ki Hunng^* and HONG, Sa Uk^(**)(^*Coll. of Pharmacy, Seoul Nat. Univ and ^**Coll. of Pharmacy, Sungkyunkwan Uuiv.) Limnological study of Kwangneung river in winter season. Kor. Jour. Bot. Ⅶ (1):15-19, 1964. In this stndy, we examined the quality of water and the kinds of algae and insects the Oksukchon river along the length between Kwannung and the Han river during winter. Also examined is the relation between the quality of water and the flesh water plants in sevral significant points along the Oksukchon river between Kwannung and the Han river. We dicovered that the gradual pollution of the quality of water in places near vilages and towns reasulted in a considerable change of life in water. The present qualiy of water skows a remarkable difference from the limnological report of the winter of the year 1960^((8)) which we previously reported, and a cosiderable change in kinds of fish and water plant since then were noticed.