This paper deals with the mathematical modelling of the random scission of branched chains. The objective is to predict the reaction products as well as the molecular weigth distribution for processes such as the chemical modification of polyolefins by free radical mechanism. In comparison with linear chains, where the number of scission possibilities is clear and scission products are linear, for branched chains the problem is much more complex. Two modelling approaches for branched chains were used. The first one, a kinetic, deterministic approach assumes a simple, regular morphology for all chains in order to compute its effect on the process. The second, more realistic approach uses Monte Carlo methods, and is able to keep track of the structure of each chain during the scission process. Stars and combs were used as idealized structures in the simulations with both approaches. The two approaches are applied, compared and discussed. The simulated results show that the chain morphology plays an important role in the scission of branched chains.