Investigation to find out the amount of variability present in the Crossandra [Crossandra infundibuliformis (L.) Nees] was carried out at Horticultural College and Research Institute, Periyakulam during 2016-17 using local Nilakottai genotype. The mutagens employed were gamma rays at different estimates of phenotypic variance (phenotypic variation) were higher compared to the genotypic variance (genotypic variation) for all growth and flower characters, indicating the influence of environment. Among the morphological characters studied, high (phenotypic and genotypic variation) were recorded for a number of flowers per plant. Whereas all the other traits showed moderate to low values. All the traits recorded very high heritability in M₂ generation in mutant populations of Nilakottai local. The genetic advance as per cent of the mean was high for plant height, number of leaves, internodal length, number of branches, length of the branch, number of days for first flower to emerge, number of spikes per plant, number of flowers per spike, number of flowers per plant, length of spike, yield of flowers per plant, weight of 100 flowers. High heritability values recorded for all the traits measured indicates that genetic variation can be created using Nilakottai local thus ensure continuous improvement through breeding of Crossandra plant.