Nine fungi causing blight or foot-rot diseases of pea, gram, lentil and vetch (Vicia sativa) have been studied. The symptoms of disease and nature of injury caused, as observed on naturally or artificially infected plants, have been described. A comparative study of the various fungi has been made as regards the following: Morphology on the natural host and on various artificial culture media. Response to environmental conditions, such as nature of medium, acidity of medium and temperature. Manner of spore germination under a variety of conditions. Inoculation experiments by three different methods under glasshouse and field conditions have been carried out. The main results were: Each fungus with the exception of Mycosphaerella pinodes and Ascochyta pinodella is specialised largely to its own host plant. Mycosphaerella pinodes and Ascochyta pinodella are the only ones which cause severe foot-rot. A discussion of the experimental results in relation to the taxonomy of these forms is given, and the following conclusions are reached: The fungus causing blight of peas in India is typical Ascochyta Pisi Lib. The fungi isolated from lentil in India and from wild Vicia sativa in England are varieties of Ascochyta Pisi Lib. The fungus causing blight of gram in India is identical with Phyllosticta Rabiei (Pass.) Trotter. Reasons are given in support of the transference of this species to Ascochyta as Ascochyta Rabiei (Pass.) Labrousse. Ascochyta pinodella Jones and Ascochyta pinodes Jones (perfect stage = Mycosphaerella pinodes (Berk. & Blox.) Stone) are confirmed as good species and distinct from Ascochyta Pisi Lib. and Ascochyta Rabiei (Pass.) Labrousse. The two former are characteristically associated with the foot-rot phase of the disease and are both rather unspecialised in their parasitism. A fungus isolated from peas in India, in association with Ascochyta Pisi Lib., is considered to be a weakly parasitic race of Ascochyta pinodella Jones.