To evaluate changes in proline, soluble sugars and chlorophyll accumulation, catalase (CAT) and ascorbate peroxidase (APX) activity under different irrigation regimes at two growth stages on potato (Solanum tuberosum L.), a factorial experiment was carried out based on complete randomized design (CRD) with three replications in greenhouse condition. Experimental factors were irrigation regimes at four levels of field capacity (I₀=100%, I₁=80%, I₂=60% and I₃=40% FC) and growth stages at two levels (GS₁=50% emergence to 50% flowering, GS₂= 50% flowering to physiological maturity). The results showed that irrigation regimes highly affect proline content, soluble sugars and catalase activity at 1% level. Studied traits were not affected by growth stages. Interaction between irrigation regimes and growth stages was not significant for any studied traits. Mean comparison of treatments showed that maximum content of proline(4.94µmol g^1-dw) , soluble sugars(55.99 mg g^1-dw) and catalase activity(12.75µmolH₂O₂min) were related to 40% FC (I₃) irrigation regime. The highest significant correlation observed between total chlorophyll with chlorophyll a (0.86) and catalase activity with soluble sugars (0.81). It was concluded that studied physiological characteristics of potato severely affected by irrigation regimes, and 40% FC treatment had the highest effect on studied traits.