Based on review of literature on Unani Medicine and contemporary scientific investigations, the study demonstrates enormous potential of common Indian earthworm to combat many human ailments. The information on clinical, pharmacological and chemical studies carried out on earthworms between 1930 and 2009 in India and abroad has been reviewed in an effort to substantiate their medical efficacy. In this paper, the methods of collection and processing of earthworms, their pharmaceutical composition, preliminary pharmacological and clinical effects on (i) nervous system; (ii) blood circulatory system; (iii) cardiovascular system; (iv) respiratory system; (v) uterus smooth muscle function; and (vi) anticancer properties are reviewed. Therapeutic efficacy of earthworms has been shown for tracheitis and bronchial asthma, epilepsy, high blood pressure, schizophrenia, leg ulcers, mumps, eczema, urticaria and anaphylaxis diseases, burns and scald fractures, erysipelas, sequel of encephalitisB, chronic lumbago, skin crevices, blood deficiency apoplexy, acute injury of soft tissues, vertigo, hematemesis and hematuria, digestive ulcer, vesicle calculus and cancer. Taking lead from the present reports detailed scientific investigations are needed to discover new therapeutic agents of zoological origin which might be very specific to treat certain diseases and conditions, thus far, incurable in modern medicine.