The nonlinear optical properties of a new class of strained‐layer superlattices (intrinsic Stark effect superlattices) have been investigated. Specifically, we have compared the nonlinear transmission of Ga1−xInxAs‐GaAs strained‐layer superlattices grown along the (211) axis to identical superlattices grown along the (100) axis, and found that the optical nonlinearity in the (211) sample is about one order of magnitude greater than in the (100) sample. A blue shift of the exciton resonance and an increase in the exciton absorption strength in the (211) sample with increasing light intensity was observed (attributed to screening of the intrinsic Stark effect fields by photogenerated carriers), resulting in the stronger optical nonlinearity. The maximum of the nonlinear absorption index, ‖&agr;2‖, in the (211) sample was 54 cm/W (‖Im &khgr;3‖=0.33 esu) whereas in the (100) sample the maximum of ‖&agr;2‖ was 6.9 cm/W (‖Im &khgr;3‖=0.042 esu). The measured carrier recovery time in both samples was 2 ns.