Background and Objectives: To study the role of Serum Lactate Dehydrogenase (LDH) as a diagnostic parameter in gastrointestinal tract (GIT) carcinoma patients. To compare the level of serum Lactate Dehydrogenase in metastatic and non metastatic Gastrointestinal tract carcinoma patients. To evaluate preoperative and post operative serum Lactate Dehydrogenase level in Gastrointestinal tract carcinoma patients. Materials and Methods: Studied 20 patients of Gastrointestinal tract carcinoma admitted in surgical ward were selected for study group. Out of 20 patients, 15 patients were Gastrointestinal tract carcinoma without metastasis. 5 patients were Gastrointestinal tract carcinoma with metastasis. 20 healthy individuals were included in the control group. The correlation of serum Lactate Dehydrogenase levels in pre operative and post operative Gastrointestinal tract carcinoma patients were studied. Results: Serum Lactate Dehydrogenase levels were elevated in pre operative GIT carcinoma patients with and without metastasis. Serum Lactate Dehydrogenase levels were decreased in post operative patients of Gastrointestinal tract carcinoma without metastasis but elevated in postoperative patients with metastasis. Conclusion: The study showed serum Lactate Dehydrogenase as an independent diagnostic and prognostic bio marker.