Steady and transient nonlinear melt-state viscoelastic properties of poly[(butylene succinate)-co-adipate] (PBSA), a biodegradable polyester, are investigated. Experimental data are compared with predictions of a rheological model developed by Ait-Kadi et al. (J Rheol, 1999, 43, 51-72). The results show that the model predicts very well the steady state shear viscosity and the normal stress difference. A good agreement is observed also for start-up and relaxation shear viscosity. A less satisfactory agreement between model predictions and experimental data is found for the transient normal stress difference. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 832-839, 2010