A semi‐empirical procedure is described to represent the effects of blade sweep angle on the airloads during dynamic stall of an airfoil. The procedure is consistent with a previously derived unsteady aerodynamic model for lift, pitching moment, and drag prediction of a blade section within the context of helicopter rotor aeroelasticity and performance analyses. It has been concluded from the present study that sweep angle primarily affects the nonlinear airloads by modifying the local development of trailing edge flow separation; the subsequent behavior of the airloads, under both steady and unsteady conditions, appears as a consequence. Justification of the modeling is conducted with experimentally obtained dynamic stall data for a NACA 0012 airfoil oscillating in pitch at a Mach number of 0.4 with steady sweep angles of 0° and 30°. Excellent correlations were obtained with the test data, and these provide increased confidence in the validity of the unsteady aerodynamic model for the helicopter rotor environment. A preliminary method is also suggested to account for time dependent sweep effects.