Total soluble proteins were extracted from commercial Egyptian cotton Gossypium barbadense, that are genetically characterized as heat tolerance varieties e.g. Giza 80, and Dendera and as heat sensitive varieties e.g. Giza 45 and Giza 85, and examined on One-Dimensional SDS-PAGE. Total soluble proteins examination showed that the control temperature protein pattern is still present in the heat shock treated samples. However, the heat shock induced proteins are present in greater abundance at different molecular weights (20 KD-67 KD). Comparing protein patterns of the heat shock treated plants at (45°C) with the control one which grow normally at (30°C) showed differences of polypeptides profile that disappear at molecular weight (45 KD) and others that appear at molecular weight (20 KD and 70 KD). The protein pattern synthesized in-vivo for control temperature showed similar pattern to the induced temperature in addition to some differences were shown at molecular weight (36KD). In vivo-labelling protein experiments for seedling tissue indicated the presence of appreciable amounts of proteins in the control lanes of Giza 80 that co-migrate with HSP 67. The authors observed no differences in the amount of this class of HSPs synthesized by the utilized Egyptian varieties. Polymerase chain reaction (PCR) analysis for the Egyptian cotton varieties genomic DNA using hsp's oligonucleotide primers combinations desiegned from gene bank data base indicated the presence of the previous homologous hsp's protein sizes as indicated in the In-vivo labelling protein analysis. This data suggests that proteins which accumulated in cotton leaf and seedling tissue in response to elevated temperatures are HSPs, and can accumulate to substantial levels in field plants and cause its thermotolerance capability. Examination of the proteins synthesized at control temperature did show some differences between varieties, possibly due to the presence of HSPs.