Heat shock protein 70 (HSP70) is a crucial protein with vital biological tasks in cell continuation of life. The variation of HSP70 activation occurs as a consequence of stress that includes temperature states, toxicity, poisoning with heavy metals, and tumor-related conditions. One of the master jobs of the HSP family is the suppression of caspase-mediated apoptosis signals. A high level of the expression of HSP70 is accountable for tumorigenesis and resistance against chemotherapeutic drugs. For this reason, the detection of HSP70 may help to diagnose cancerous diseases. From the other side, targeting this chaperone might help in treatment by maintaining late caspase-dependent events. This study was conducted to detect the presence and the location of HSP70 in Iraqi thyroid tumor tissue specimens (25 samples), in addition to 10 samples of normal thyroid tissue. Using the immunohistochemical study (paraffin method), the protein was detected in 100% of follicular carcinoma or follicular adenoma (benign) in addition to 77.7 % of papillary thyroid carcinoma while, in normal thyroid tissue, the presence of protein was in 10 % of cases. Regarding protein location in the cells, it appeared in the nuclei and the cytoplasm of follicular carcinoma cases in comparison with just in the cytoplasm of other sections.
