As a further contribution to the study of the relative efficiency of various phosphates for corn, the authors report the results obtained in two experiments located on different areas of the Pindamonhangaba Agric. Exp. Sta., State of São Paulo, one of which was carried out in 1953-54 and the other in 1954-55. In both soils, highly responsive to phosphorus, the natural phosphates Hyperphosphate, Serrote-phosphate (from Juquiá, State of São Paulo), Florida-phosphate and especially Olinda-pfiosphate (from the State of Pernambuco) were much inferior to superphosphate. Inthe first trial, whose yields were generally very low, bone meal proved equivalent to superphosphate, but in the second, which was conducted under conditions favorable to much higher yields, it was fairly inferior to superphosphate.