Proper design of lime-treated subgrade requires knowledge of the stress-strain behavior under repeated traffic load. Limited research exists regarding the resilient modulus (MR) of lime-treated expansive soils. This study investigates the effect of lime treatment on the MR of an expansive soil from city of Tabuk in Kingdom of Saudi Arabia. Tests were performed in accordance with AASHTO T-307. Tests variables included lime content (2%, 4% and 6% by dry weight of soil) and curing period (7 and 28 days). Experimental results mainly revealed an increase in M_R values due to lime treatment. In addition, the variation of M_R with deviatoric stress revealed trends of strain softening behavior in case of untreated soils and lime-treated soils cured for 7 days. However, lime treated soils cured for 28 days experienced some strain hardening behavior with high dependency on confining pressure. Furthermore, the M_R of lime treated expansive subgrade was observed to be highly dependent on lime content and curing period. Finally, results were fitted using the three-parameter model to determine the stiffness coefficients (k₁, k₂, k₃).