Japanese beef production is characterized by its large percentage of dairy beef. In 1981, about 71 percent of the beef production was accounted for by dairy beef of which more than half was derived from dairy bull cattle for fattening. In order to increase the beef production, it is very important tot stabilize the profitability of dairy bull cattle feeding farms. The objective of this study is to identify the structural characteristics and the factors contributing to profitability of dairy bull cattle feeding management in Fukuoka Prefecture. This study is based on data derived from farm records of the Survey on Production Costs of Dairy Bull Cattle for Fattening in Fukuoka Pref., which was conducted by the Ministry of Agriculture, Forestry and Fisheries of Japan(MAFFJ) in 1980. The results of this study can be summarized as follows: 1. Average herb size of the cattle feeding operations was 47 heads in 1982. About 10 percent of the cattle on feed was fattened by dairy farmers. 2. Almost 75 percent of the cattle and 13 percent from rice. Average fattening period was 11.8 monthsand daily gain was 1.0kg. 3. Feeder cattle, commercial feed, and family labor accounted for 39 percent, 41 percent, and 10 percent of the total production cost per head, respectively. Cattle feeders recorded a high profitability untile 1980, but they suffered from a large loss in 1981. This loss resulted from price fluctuations of feeder cattle and fed cattle. 4. The total production cost per fed cattle decreased only slightly as the herd size increased because most of the itemsused in cattle feeding, except labor and litter, fell into the category of variable costs. But scale economy in labor input contributed largely to increasing labor return per day and labor productivity. 5. It was found that extending the fattening period lowered the daily gain and increased the total production cost per unit of live weight. But fed cattle price per unit of live weight tended to increase with an increase in length of the fattening period. This fact appeared to encourage the cattle feeders to extend the fattening period. But the ratio of fed cattle price to total production cost and the labor return per day didn't always increase as the fattening period extended. 6. Labor return per day increased with the increasing price of dressed carcasses, but the rate of increase was found to be less in the case of small scale cattle feeders than in the large. Because of this, it seems that the small scale cattle feeders make efforts to increase profitability by extending the fattening period and by using too much commercial feed and labor. But this may cause the instability in profitability. 7. The break-even point of the cattle feeding was found to be located at a high level, 92 percent of the gross income. To increase profits, cattle feeders must lower the position of the break-even point.