The mathematical description of polymer chain scission given by N. M. Emanuel' & D. C. Knorre (Chemical Kinetics (Homogeneous Reactions), John Wiley, New York, 1973) is shown to be inaccurate and an alternative formulation is presented. The model of collagen degradation proposed by T. E. Rudakova & G. E. Zaikov (Polym. Deg. Stab., 18 (1987) 271) which is based upon the work of Emanuel' & Knorre is modified accordingly. The revised model is applied to the results of experiments on the effect of hydrolysis on collagen sutures and is found to fit the data only during the early stages of degradation. Possible causes of the lack of fit of the conceptual model are discussed.