This work aimed to study the effect of ethephon in the sex expression in tetsukabuto type squash plants. The experiment was conducted using a randomized complete block design, in a factorial analysis (3 x 4). The first factor was the ethephon doses (100, 200 and 300 mgL-1) and the second the number of weekly applications (1, 2, 3 and 4). Ethephon promoted a temporary ginoicism, reducing considerably the labor of male flower elimination in female parents. A reduction was observed in the ratio between male and female flowers and the increasing doses. In addition, female flowers tended to increase in the early nodes. Doses of 300 mgL-1 of ethephon applied three or four times was the best treatment and might be used for squash hybrid seed production.