Callus cultures were established from immature leaf explants of Arachis hypogaea on MS medium supplemented with 2.0 mg/L of NAA and 0.5 mg/L of EAR of the susceptible cultivars namely VRI-2 and TMV-7. Three-week-old calli were subjected to mutagenic treatments (gamma rays : 50-250 Gy and EMS : 5-25 mM). Mutagen-treated calli were subcultured to fresh medium containing various concentrations (25-100% v/v) of pathotoxic culture filtrates. Calli were challenged in vitro with pathotoxic culture filtrate of the fungal pathogen and were assessed by visible growth ratings expressed as the percent response to the doses/concentrations of mutagen. Selected mutagen-treated calli showed resistance in vitro on media containing Cercosporidium personatum pathotoxic culture filtrate. Resistance calli were then transferred to MS regeneration medium supplemented with BAP (2.0 mg/L) and NAA (0.5 mg/L) for shoot bud regeneration. The progeny of the plants produced 13 disease-resistant plants (R(2)) in both the cultivars. Among the eight R, populations studied, 70.2-82.5% of the plants exhibited enhanced resistance. This study suggested that groundnut plants with resistance to C, personatum can be selected from mutagen-treated callus of tikka leaf spot-susceptible cultivars using host-specific pathotoxic culture filtrates of C. personatum through in vitro technology.