A majority of Indian population (40%) is vegetarian and pulses are playing an important role in providing protein (22%) and other essential nutrients to the large population of the country. Among them, pigeonpea [Cajanus cajan (L.) Millsp.] is one of the important legume. Pigeonpea leaf blight caused by Alternaria tenuissima is one of the most important foliar disease causing heavy losses under South Gujarat region. During the last few years blight has been occurring almost every year, essentially due to the soil-borne survival of the fungus, local overwintering/oversummering of inoculum, cultivation of susceptible varieties and favorable environmental conditions.Considering the high economic damage and frequent occurrence of spots and blight caused by alternaria in field, the detail study was carried out on alternaria leaf blight of pigeonpea.