An investigation to study the influence of gamma rays as seeds exposing (0 , 1, 5,10, 15 and 20 kr) and N – Nitroso – N – Methyl Urea (NMU) as seed soaking in concentrations (0.0, 30, 60, 90, 120 and 150 ppm) on Lathyrus odoratus, it was conducted at the Experimental Farm of Fruit and Ornamental Plants Breeding Research Department, Horticulture Research Institute, ARC, Egypt during the two consecutive seasons of 2012/2013 and 2013/2014. The two experiments were arranged in randomized complete block design (RCBD) with three replicates. In M₁-generation, the results revealed lower in seed germination percentage, plant height, leaf chlorophyll content and number of flowers with increasing doses and concentrations of physical and chemical mutagens. However, the effect of mutagens on leaf length and flower anthocyanin content was insignificant at M₁ and M₂-generations. The higher doses of gamma-rays and concentrations of NMU led to delay the flowering date in M₁ and M₂-generations, decrease the seed germination percentage in M₂-generation,while lower doses and concentrations caused an increase in plant height, number of branches/plant, number of leaves/plant, number of flowers/plant and leaf chlorophyll content in M₂-generation. The variations means squares indicated insignificant difference between gamma-rays and NMU in M₁ and M₂-generations, in seed germination percentage, number of branches per plant, number of leaves per plant, flowering date and number of flowers per plant. However, higher variation was observed between gamma-rays and NMU in M₁ and M₂-generations, for plant height, leaf length and leaf chlorophyll content. The obtained results clearly indicated that different doses and concentrations of mutants can be effectively utilized to create variability for plant height (dwarfeness plants and compact) fasciata, chlorophyll mutation, leaf shape and flowers cluster length of sweet pea plants.