HIF 1α is the intrinsic survival factor of dysplastic and tumour cells, to overcome the oxygen and nutrient deficits in the progression of OED and proliferation of OSCC. The entire spectrum of HIF 1α in OED and OSCC is not yet understood. The present study was done to evaluate the nature of expression of HIF 1α in OED and OSCC. AIM:The study aims to evaluate the IHC expression of HIF 1α in OED and OSCC and also to investigate whether HIF 1α can be a predictive marker for malignant conversion of oral premalignant lesion. OBJECTIVES:To analyse the IHC expression of HIF 1α quantitatively and qualitatively in OED and OSCC and to compare HIF 1α expression in OED and OSCC. Materials and methods: Neutral buffered formalin fixed paraffin embedded blocks of 30 OED, 30 OSCC and 10 normal buccal mucosa cases that fall into WHO criteria were retrieved from the archives in the Department of Oral Pathology, Vishnu Dental College Bhimavaram. Clinical data was taken from the submitted biopsy forms. IHC staining of HIF1α was done according to the protocol. Quantitative, Qualitative and Semiquantitative assessment of the staining was done with the help of image J software and statistically analysed by SPSS software. Results: Of the 30 stained HIF1α OED cases, 25 expressed HIF 1α positivity, of which 9, 7 and 9 were mild, moderate and severe OED respectively, accounting for 83.3% of staining.HIF 1α stained 30 OSCC cases, showed positivity in 22 cases, of which 7, 8 and 7 were Well, Moderately and Poorly Differentiated OSCC respectively, accounting for 73.3% of staining. Conclusion: HIF1α a major contributor to tumor progression, is different in its IHC expression during different stages of OED and OSCC. Further studies could predict clinical outcome and survival of patients.