This work was carried out in The Central Lab. of Date Palm Research and Development, Agricultural Research Center, Ministry of Agriculture, Giza, Egypt during 2005-2006. This investigation was planned to study the effect of auxins (IAA, IBA and NAA), growing stages (plantlet root system ) and stem diameter on acclimatization of date palm (Phoenix dactylifera L) Zaghloul cv derived from in vitro under the different temperature and humidity treatments. The viability of acclimatization was significantly differing depending on plantlet growth stage, auxin type and level; being optimum for plantlets which formed complete root system (primary + adventitious + side roots). The best results when using 15 p.p.m of IBA for 45 seconds and plantlate stem diameter with <3 cm grown under 27 C and 90 % RH had the highest survival % during 4 months of the acclimatization.