Fertilizer induced salinity adversely affects plant growth through its ionic and osmotic effects as in ordinary salinity caused by toxic ions (Na, Cl, etc.). In this study, to determine the ionic and osmotic effects of fertilizer induced salinity and NaCl salinity on growth, ascorbic acid, proline and hydrogen peroxide (H2O2) accumulation and stomatal resistance (SR), relative water content (RWC), malondialdehyde (MDA) contents of tomato and pepper plants subjected to different treatments (i.e. control, 40 mM NaCl salinity and excess fertilizer salinity) were investigated under greenhouse condition. The results of this study indicated that similar to NaCl salinity, fertilizer induced salinity significantly reduced the fresh and dry weights of tomato plants. Relative water content of the plants was decreased by NaCl salinity. Both NaCl and fertilizer induced salinity caused significant increases in proline, MDA, ascorbic acid and H2O2 accumulation, and stomatal resistance of the plants. Salinity achieved by NaCl and fertilizer altered plant growth and plant physiological processes ionically and osmotically in a similar manner.