Farmers in the North-EasternThailand have suffered bitterly from poverty because of the unfavorable agroecological conditions. However, the irrigation development in this region has brought some changes in agriculture. In Khon Kaen Province the acreage of cultivated land has been expanded at a remarkable rate. But in the surveyed villages, the expansion of cultivated area in recent years was little. The data from the farm survey of 75 households show that the irrigation facilities brought about the decrease of damage from drought as well as the increase of average rice yield. The youngsters in their teens which consist of a high percentage of the population in the area will increase more number of the farm households after their marriage and as a result the amount of farm land per household will eventually decrease. By introducing the irrigation system into the rain-fed area it will become possible for farmers to support their families on a smaller size of farm.