Background: Lactate dehydrogenase (LDH, L-lactate, NAD+ oxidoreductase, EC1.1.1.27) is a family of at least six NAD + -dependent isoenzymes (LD1-LD5 and LD6/LDX). It is recognized as being one of the most common enzymes in nature. It belongs to the class of oxidoreductases and it is characteristic for the final stage of anaerobic glycolysis. Aim of the study: To evaluate the efficacy of lactate dehydrogenase as an indicator of liver tumors. Materials and methods: The present study was performed in the Department of Biochemistry, Kidwai Institute of Oncology, Bengaluru, Karnataka, India. For the study, a total of 100 patients were selected. The age of the patients ranged from 18 to 40 years. Briefly, 20 µL of each patient serum was mixed first with 1000 µL of buffer (pH 7.35) supplied by the manufacturing company and incubated for 1-5 min at 25 °C. A volume of 250 µL of substrate that composed of nicotinamide-adenine dinucleotide (0.75 mmol/L) and sodium azide (0.095%) was added to the mixture. After mixing, the absorbance at 340 nm was read by UV-visible spectrophotometer (CECiL, CE 1021, England) after 1 min. CK levels were assayedaccording to Humazym M-test as described by the instructions of the produced company