Abstract Mutagenic effects of gamma-rays and N-nitroso- N-methyl urea (NMU) were studied for the induction of macro- and micro-mutations in M 2 and M 3 generations of lentil. Estimates of variability for morphological or production traits were larger in the mutagenised populations than the untreated controls. The magnitude of the induced genetic effects was comparable at doses of gamma-rays and N-nitroso- N-methyl urea causing similar reductionsin plant survival. There was no relation between the mutagen treatments, which produced the highest frequency of macro-mutations, and the doses inducing the most micro-mutations. The higher values of predicted heritability and genetic advance suggested that the mutations have mostly occurred at loci having additive effects. A comparison of the correlations in M 3 generation grown from the selected M 2 populations and the control revealed that interrelationships between yield and its component traits increased. The results suggested that the mutagenic treatments plus selection could increase the strength of the correlatis between any two characters.