Alternaria blight incited by Alternaria brassicae (Berk.) Sacc. is wide range fungal pathogen that can infect the foliar and seed borne pathogen in crucifers. Molecular Diversity of Alternaria brassicae populations were fundamental to the understanding of epidemiology, host– pathogen interaction and resistance management. The present study was aimed to reveal genetic variability among 20 isolates of the Alternaria brassicae isolates collected from the state of Madhya Pradesh, by using Random Amplified Polymorphic DNA (RAPD) molecular markers. A total of 174 reproducible and scorable bands ranging from 100-3000 bp (base pair) were generated for all twenty A. brassicae isolates with 20 RAPD primers. The highest numbers of bands (15) were produced by primer OPE-03 while, lowest numbers of bands (4) were produced by primer OPA-13. The numbers of polymorphic bands produced were maximum (14) with the primers OPU-03 while minimum (1) with primers OPA-13 and OPA-19. On the basis of RAPD data the total percentage of polymorphism was 78.36% among all the isolates. RAPD marker based dendrogram categorised twenty A. brassiace isolates into two groups.