The correct diagnosis of disease is essential for curing of diseases. Most of the diagnosis is depends on pathological laboratory test. Proper diagnosis is a key to success in medical practice. Roganidana (Ayurvedic Diagnostics and Prognosis) & Vikriti Vijñana((Pathology) is part of Ayurveda (Indian System of Medicine) that deals with the understanding of the diseases based on the fundamental concepts with pathophysiology of disease processed. The subject Roga Nidana and Vikriti Vijñana is part of Professional BAMS degree. This book included descriptions of Medical laboratory test in various diseases with its clinical significance and dhatu, mala pariksha (examination) according to Ayurveda, as well as the pathophysiological variation in result of laboratory practical. Also brief description of clinical instrument that use in medical laboratory practical and clinical examination of patients.