Abstract: Firefly Algorithm is a stochastic and meta heuristic approach inspired from nature having a wide range of applications in solving various optimization problems. Firefly Algorithm (FA) suffers from problem of slow convergence speed. This problem can be solved by using modified Firefly algorithm called as Enhanced Firefly Algorithm. By using this algorithm side lobe level of rectangular antenna array can be reduced considerably without appreciable effect on beam width. SLL is most important array pattern parameter because reduced SLL results in minimizing received noise and interference. Low SLL in the radiation pattern of the rectangular antenna array can be achieved by considering phases and amplitudes of the excitation currents of elements of array as variables to be controlled having fixed spacing between the elements. In this paper SLL of symmetric rectangular array antenna is optimized using Enhanced Firefly algorithm (EFA) and its results are compared to the results obtained with Genetic Algorithm.