The disease lathyrism is being caused by the poisoning of the peas of genus the Lathyus such as L. cicerc, L. clymenum and L. satritis. The history of the disease is being treated from the time of Hippocrates. Reports the record of the disease in various parts of the world. The cause of pathological changes in this disease is not well defined. Describes the presence of selenium contained in the soil, contamination of lathyrus from the weed Vicia satva and the toxic substances of Lathyrus as the possibilities. The paper includes detailed botanical study of flora of Lahore W.P. which reports presence of L. Sativus in the area. The toxicity attributed to the alkaloid present in this herb. The bio-chemical components of lathyrus are enumerated. The paper also gives pathology, clinical features, differential diagnosis, prognosis, treatment and suggests, preventive measures.