Treatments with colchicine in peanuts have been tried on seed, coty-ledonary buds and on seedling main stems previously cutted. Polysomatic roots were observed in F2 plants, but there was not any evidence of polyploidy in other parts; some treatments produced irregu-lary larger pollen grains. Phenotypic modifications were observed: some plants with few and long branches as well as others with very short ones, all them being sterile; seedlings with abnormal hypocotyl and thick roots, that died few days after germination; plants which produced catenate fruits similar to those of Arachis monticola;and plants with larger and more regular seed than the original variety. No association was found between the phenotypic modifications and polysomaty or abnormal pollen.