The aim of this book is to focus on the essentials of internal medicine. The primary aim of this book is to develop a compelling basic textbook in internal medicine which would provide a solid understanding of the pathophysiology of diseases, help in the development of strong clinical acumen in approach of common clinical syndromes and make one confident about management of different diseases of various organ-systems. This book comprises of 14 sections following as cardiovascular system, central nervous system, nephrology, respiratory system, gastrointestinal system, rheumatology, hematology, endocrine, diabetes (endocrine), dermatology, infective diseases, miscellaneous, psychiatry, and examinations which consists of 127 chapters. Its include electrocardiogram, valvular heart disease, hypertension, cardiomyopathy, ischemic heart diseases, meningitis, coma and related disorder, motor neuron disease, acute glomerulonephritis, chronic renal failure, urinary tract infection, chronic obstructive pulmonary disease, acute respiratory distress syndrome, bronchogenic carcinoma, pneumothorax, approach to a patient of upper gastrointestinal bleeding, approach to a patient with malabsorption, approach to a patient of monoarthritis, approach to a patient of anemia, thyroid gland disorders, examination of upper gastrointestinal tract, and examination of lower gastrointestinal tract. This book is useful companion to the undergraduate students as well as postgraduate trainees.