Free polyamine contents and expressions of five genes encoding for polyamine biosynthetic enzymes were investigated at four different stages during peach (Prunus persica L. Batsch cv. Akatsuki) flower development. Fresh mass of peach flowers increased, accompanied by reduction in contents of total polyamines and putrescine/spermidine ratio due to decrease in putrescine content. Spermidine, the largest fraction, and spermine, the least part, underwent minor change. Expressions of the five key genes involved in polyamine biosynthesis during flower development did not parallel the changes in free polyamines.