The main feature of the semperflorens mutant of Coffea arabica is its ability to produce flowers during the whole year, whereas other commercial types of the same species have a definitive flowering period. In the S. Paulo plateau this occurs only at the beginning of the rainy season, August-October. The yield of several progenies of the semperflorens coffee, the period of fruit development, and the size and types of seeds produced were recorded for a few years in plantings made in three localities of the state of S. Paulo: Campinas (1940-1951), Ribeirão Prêto (1939-1941), and Pindorama (1945-1950). The average plant yield in Campinas was 3.140 kg of ripe fruits per year; in Pindorama, 2.740 kg; and in Ribeirão Prêto, 1.660 kg. A comparison of the semperflorens coffee with selected strains of Red Bourbon indicated that the anual yields of the former variety were lower in spite of its giving several crops a year. When harvests were made at monthly intervals to study yield distribution throughout the year, two peaks were recorded: (1) one around April for the three localities; (2) another in November for Campinas and Ribeirão Preto, and December-February for Pindorama (Tables 1, 4, and 6). The average number of days from flower anthesis to ripe fruit varied from 188 to 271 days. The shortest periods of fruit development were generally those for flowers opened from September to January and the longest for the February-June flowers (Table 9). An analysis of ripe fruits attacked by the berry borer (Stephanoderes hampei Ferr.) showed a high infestation during July-August and a low one in January-February. A heavy infestation occurred in 1947 and 1948 (Table 10). The semperflorens seed size was larger in June and smaller in December, at Campinas. The weight of 100 flat seeds showed little variation and averaged 10.52 g. In 1941 this value was lower than average (Table 12) corresponding to a low yield and small size of the beans. The average bean weight was higher from April to July than in the remaining months. No correlation was found between seed weight and average monthly yields, but there was a positive and significant correlation between seed weight and size. The semperflorens seed was smaller than comparable seed from typica and Red Bourbon. The amount of peaberry seed type found on semperflorens varied from 3.5 to 23.04 per cent (Table 13) with higher values in June and July when the yields were low; lower values were recorded for the harvest from October to December when the yields were high. Due to its continuous flowering, the semperflorens has been used in crosses with mutants of Coffea arabica which usually produce a low number of flowers. It has also been used as a graft partner for coffee mutants with scarce flowering. In spite of having some advantages as resistance to drought, the semperflorens selected strains are not being recommended for establishment of coffee plantations because of their low yielding ability. Hovewer, it is suggested that this coffee type should be maintained in all coffee collections for genetical and physiological research work.