Ethephon [(2-chloroethyl)phosphonic acid] applied at seedling stage of a monoecious and a gynoecious cucumber reduced internode length. The rate of increase and the total increase in cumulative fruit number was significantly higher, compared to the untreated plants in the monoecious, but not in the gynoecious cultivar. Preflowering treatments of both cultivars caused simultaneous development of numerous lateral shoots. There was also a significant increase in the number of nodes especially on side branches. Preflowering treatments generally excelled seedling treatments and the control in total number of fruits. Preflowering application of 150 ppm ethephon to the monoecious and 250 and 350 ppm rates to the gynoecious cultivar resulted in higher cumulative fruit number at each and every one of the 9 harvests during the 18-day harvest period. Ethephon treatments lowered percent fruit set in the monoecious cultivar.