Lentil is the second most important pulse crop in Iran's rainfed and dryland areas. In 2015, a severe blight disease was observed on the crop in the main lentil-producing regions of the country, leading to complete defoliation and a yield loss of over 80%. Studies using morphological and molecular approaches identified the disease agents as Stemphylium beticola and Alternaria alternata. To determine appropriate fungicides, a research study was conducted from 2018 to 2021 in the field conditions of Moghan and Gachsaran provinces located in the hot spots of the North-West and South-West of the country, respectively. Five fungicides were tested in two concentrations each, including Iprodione + Carbendazim 52.5% WP at 0.75 and 1.0 kg/ha, Propiconazole 25% EC at 0.75 and 1.0 L/ha, Signum 33.4% WG at 0.75 and 1.0 g/ha, Mancozeb 80% WP at 1.0 and 1.5 kg/ha and Chlorothalonil 75% WP at 1.5 and 2.0 kg/ha. The experiment was also repeated in the glasshouse with the same concentrations and in vitro using agar-dilution method with 0, 10, 20, 40, and 60 ppm of fungicidal concentrations. Results showed that Signum (R) was the most effective chemical compound for disease control. However, based on economic analysis, Mancozeb and Chlorothalonil at a concentration of 1.5 kg/ha are recommended for disease control in the hot spots, respectively.