Abstarct: Delaying the time of flowering in apricot trees in the areas where there is a risk of spring frost is very important. In this study, the effects of ethephon and soybean oil was investigated at the time of flowering of two Iranian apricot cultivars. A factorial experiment was conducted on the baxse of RCBD design with 3 replication. The first factor was two apricot cultivars, Rajab Ali and Khiveai, and second factor including six spray treatment: control, ethephon 100 mg/l, ethephon 200 mg/l, soybean oil 10%, soybean oil 15% and soybean oil 15% with 200 mg of ethephon. The results showed that soybean oil 15 % with 200 mg/l of ethephon delayed beginning of flowering and full bloom about seven days in compare to control. The time of flowering in trees which sprayed with 10% and 15% of soybean oil only 1 day different to control. The maximum delays in the beginning of flowering and full bloom in Rajab Ali variety was observed at 15 % of soybean and 200 mg/l of ethephon spraying treatment with respectively eight and nine day delay to control. However, the maximum delay in the beginning of flowering and full bloom in the Khiveai was respectively four and five day delay at 100 and 200 mg/l of ethephon. The pre-blossom frost damage on control trees was significantly higher in compare to trees treated with ethephon. The primary and secondary fruit set was a significantly increase in ethphon treatment. Ethephon can cause late flowering, reduced frost damage and increase the percentage of fruit set that can be recommended as a practical approach to local farmers.