Abstract: Control flowering time in apricot trees is very important where spring frost damage is of high risk. Application of plant growth regulators during autumn has been suggested for controlling bloom date. This experiment was conducted during 2000-2001 to examine the effects of application of different concentrations of ethephon and gibberellic acid (0, 50, 100, 200 and 300 mg L-1) at the end of August, September and October) to delay flowering in apricot Shahroudi cultivar. A factorial experiment was laid out in Completely Randomized Block Design with 3 replications. Compared to the control results showed, 100 mg L-1 of ethephon applied at the end of October delayed full bloom approximately 3 days (2000) and 7 days (2001). Gibberellic acid applied at 300 mg L-1 at the end of August delayed full bloom about 5 days (2000) and at the end of September, l0 days (2001). During both year`s gibberellic acid and ethephon applied at the higher concentrations resulted lower percentages of flower opening and fruit set.