Background: Hypoxia-inducible factors (HIFs) are transcription factors that get activated and stabilized in the heterodimerized form under hypoxic conditions. The three members of the HIF alpha factors share high structural similarity but have tissue-specific expression patterns. A majority of studies have reported the importance of the HIF1A and HIF2A activity in the survival, proliferation, metastatic potential, and metabolic regulation of hypoxic cancer cells. However, the importance of the expression pattern and activity of HIF3A in a variety of cancers remains unknown. Method and materials: The expression profile of 13 different types of The Cancer Genome Atlas (TCGA) cancer samples were downloaded, normalized and differential gene expression analysis (DGE) was performed to compare the expression pattern of HIF alpha family members in cancer and adjacent normal tissues, as well as at different stages and tumor-sizes. Receiver operating characteristic (ROC) test and survival analysis were carried out to estimate the diagnostic potential of HIF alpha isomers in different cancers, as well as the survival rate of patients with the varying expression levels of HIF alpha factors. Results: The expression status of HIF3A was notably less in all cancer samples in contrast to their adjacent normal tissues. The expression degree of HIF1A varied among distinct types of cancer and the expression degree of HIF2A was lower in nearly all types of cancers. The expression level of HIF alpha isomers did not significantly correlate with different sizes of tumor samples and stages of different tumor tissue samples. HIF3A had very weak diagnostic potential, while HIF2A had better diagnostic potential in most types of cancers compared to HIF1A. Patients who had a higher level of HIF3A had better survival, while the higher expression levels of HIF1A and HIF2A were associated with worse survival in many types of cancers. Conclusion: Our study shows the heterogenous expression pattern of HIF alpha subunits in distinctive kinds of cancers and the influence of HIF3A expression level in the survival of patients with varying types of cancers.