Plants of the strawberry cultivar `Reiko' with an inflorescence consisting of a primary (1st) flower (fruit) or a primary and two secondary (2nd and 3rd) flowers (fruits) were grown in a chamber under controlled light and temperature conditions, and the size of each fruit was measured with a caliper at 2-day intervals from 5-7 days after anthesis. Each fruit grew rapidly in the early period (5-7 days) and late period of fruit growth, in showing a pattern characterized by a double sigmoid curve. The second peaks occurred at 35, 28 and 36 days for the 1st, 2nd and 3rd fruits, respectively, in the first experiment (16°C in the daytime (12 hr, 315 μmol m-2 sec 1) and 13°C in the night), and at 23 days for the 1st fruit in the second experiment (20°C in the daytime (14 hr, 185 μmol m-2 sec 1) and 17°C in the night). In the second experiment, at 5-9 days the achene on the 1st fruit grew rapidly. During 5-17 days the dry weight and sugar concentration per dry weight of the 1st fruit were very low, but thereafter they increased remarkably. It is considered that in the first peak of fruit growth the receptacle started to grow and the fruit set was completed due to the rapid growth of the achenes after fertilization, while in the second peak a large amount of assimilates was transported into the receptacle which enlarged rapidly again