Abstract: The demand for lily flowers has increased considerably during the last few decades, the main limiting factor in large scale cultivation is its susceptibility to a number of pathogens. The present investigation was undertaken to improve this crop by developing resistant mutant lines using in vitro cell selection technique. Resistant cell lines were selected by culturing calli derived from bulbscale segments of Oriental lily ‘Casa Blanca’ susceptible to Fusarium oxysporum on MS (Murashige and Skoog) medium supplemented with growth regulators and various concentrations of culture filtrate. After one month of inoculation about 94% of the calli showed reduction in growth. Selection was made at 15% culture filtrate level. Only 6.6% calli regenerated shoots with different concentrations of Naphthalene Acetic Acid (NAA) and Benzyl adenine (BA). Resistant calli obtained after two cycles (30 day cycle-1) of selection were used for bulblet regeneration and to check the stability the regenerated bulblets were transferred to MS medium containing 50% culture filtrate. About 75% of the resistant bulblets showed healthy growth and produced new leaves. One-year-old bulbs from selected cell lines and control were maintained in glasshouse for screening against pathogen. Thirty three plants from selected cell lines showed resistance whereas all the control plants showed morbidity or died when tested with Fusarium spore suspension. No variation was observed in the morphological characters in the selected regenerates. Resistant bulbs were developed using in vitro selection technique, which may be one of the main and effective ways of lily variation breeding with resistance to both biotic and abiotic stresses.