A study of the reproductive efficiency of five agronomical varieties of peanut was made. Determinations were made of fruit and seed percentages in relation to number of flowers procured, length of flowering period, alternation of high and low daily flower frequencies, and number of flowers which had no chance to become fruit?. Data obtained supported lhe following conclusions: (a) Varieties of the erect vegetative type were early; they began and ended their vegetative am! flowering cycles before those of the decumbent type. (b) The flowering curves showed an abrupt alternation of high and low frequencies. (c) The highest flower frequency occurred on the same day for the five varieties tinder test. (d) The erect varieties produced well located flowers (the writer calls them useful flowers) during a few weeks. For the decumbent varieties this period was longer. (e) Fruit percentages in relation to total flowering varied from 15.9% to 25.6%. Calculated in relation to the useful flowers these values varied from 25.4% to 51.3%. The seed percentages were from 12.7% to 21.5% in the first case, and from 21.7% to 38.4% in the second. (f) The var. Tatuí and Roxo gave the best fruit percentages in relation to the number of useful flowers. Tatu and B-33 gave the highest seed percentages.