Abstract: Background and Objective: Chlorophyll mutants are used as markers in genetic, physiological and biochemical investigations. The selection of effective and efficient mutagen(s) is very essential to recover high frequency and spectrum of desirable mutations. Present investigation was undertaken to understand the response of lentil variety Pant L-406 to various chemical mutagens for identifying such mutagenic-treatment causing maximum chlorophyll mutations which could eventually be exploited for inducing viable and economically useful mutations in subsequent generations. Materials and Methods: Seeds of lentil were treated with chemical mutagens namely methylmethane sulphonate (MMS), hydrazine hydrate (HZ) and sodium azide (SA) for 6 h. Three replications of 100 seeds per treatment were sown in complete randomized block design (CRBD) to raise M1 generation. The M1 plants were harvested separately and seeds sown in next season in plant progeny rows to raise M2 generation. Chlorophyll mutations were observed in M2, when seedlings were 8-15 days old. The frequency of chlorophyll mutations, mutagenic effectiveness and efficiency were determined as per the standard formulae. Results: Different types of chlorophyll mutants viz., albina, xantha, chlorina, maculata and virescent were observed in the field when seedlings were 8-15 days old. All these chlorophyll deficient mutants were lethal except maculata and virescent which produced few seeds at maturity. The MMS treatments induced the highest frequency of chlorophyll mutations followed by HZ and SA. The frequency of chlorophyll mutations was dose dependent and increased with increasing concentrations of the mutagens. ‘Chlorina’ followed by ‘xantha’ outnumbered the other types of chlorophyll mutants in all the mutagens. Higher effectiveness was recorded with HZ treatments, whereas SA was found to be the most efficient mutagen compared to HZ and MMS. Conclusion: Chlorophyll mutations, although do not have much economic importance due to their lethal nature, such a study could however, be useful in identifying the threshold dose of a mutagen that would increase the genetic variability and number of economically useful mutants in subsequent generations.