Rooted cuttings of white flowered cv. 'Purnima' and red flowered cv. 'Colchi Bahar' of Chrysanthemum morifolium were treated with gamma rays. Sectorial somatic mutations in flower colour were detected in both the cvs. Mutated ray florets (yellow colour for both the cvs) were cultured on agar-solidified Murashige and Skoog basal medium supplemented with sucrose and different combinations of BAP/kinetin and NAA. Direct shoot organogenesis was noticed within 2 weeks of culture initiation. SEM studies confirmed this direct shoot differentiation. The best regeneration was obtained on medium supplemented with 0.2 mg/l NAA and 0.5 mg/l BAP. Shoots regenerated from mutated ray florets were rooted in vitro and transferred to the field. These plants flowered true-to-explant floret colour and shape. These isolated yellow mutants were maintained vegetatively have proved to be true-to-type in two successive generations.