flowering in sympodial orchids has been achieved as a result of changes in environmental culture condition (photo or thermo-period) or after several treatment types [decapitation' application of growth regulators ]. Flowering of the monopodial F. is either photo- and thermo-period dependent or canbe induced by low temperature only. Although vernalization has been thoroughly investigated as a flowering factor, there are very few papers on temperature-induced biochemical changes in relation to flowering in F. อุณหภูมิ mediated changes in endogenous hormonal levevels,however,have been hypothesized. Changes in levels of free indoleacetic acid [IAA] have been related to flowering of orter species,as well as changes in poleamine levels . The present work was aimed at investigating the early changes in IAA and polyamine levels after cold treatment in relation to flowering of