This paper reports the results obtained in two factorial experiments designed to study the effect, on the dwarf castor beans variety IAC-38, of three spacings between the rows (1.0, 1.5 and 2.0 meters), three distances between the hills (0.5, 1.0 and 1.5 meters), and three levels of an NPK fertilizer. The experiments were conducted for two years. The largest yields were obtained with the spacings of 1.0 x 1.0 and 1.5 x 0.5 meters. For the effect of NPK, the intermediate distances, between the rows, as well as between the hills, were much better than the wider and the closer ones. After considering the observations made, the authors believe that a spacing of about 1.25 x 0.8 meters would be more adequate. Compared with that of 1.0 x 1.0 meters, it would contribute to facilitate cultivations and harvest; compared with that of 1.5 x 0.5 meters, it would afford better use of the space between the rows and reduce the crowding of the plants within the rows.