A field experiment was carried out at the Copersucar experimental Station in Piracicaba with varieties SP70-1143, SP70 -1284 and IAC-52/150, on second ratoon stage. Ethephon was applied at 0.48 and 0.72 kg/ha, at five differe nt times from Januar y, 28 to March 15, 1985. Values of pol, brix, fiber, purity and reducing sugars, were obtained monthly from April to August. Flower emission were counted in August and the number of stalks and yield were measured in October. Ethephon caused complete inhibition of flowering in SP70 - 1143 and partial on IAC52/150 until August. SP70-1284 emited only 4% of flowers. Flowering of 50% for SP70 -1143 and of 78% for IAC52/150 did not affect the sucrose storage process. Ethephon did not affect this process either but reduced the fiber content in SP70-1284, in July, with almost all treatme nts. No differences for stalk numbers on yield were found among treatments.