A model of agglomerative crystal precipitation based on the Monte Carlo simulation technique is investigated. The processes of nucleation, crystal growth and aggregation are first simulated to obtain the particle size distribution (PSD) For continuous mixed-suspension, mixed-product-removal (MSMPR) aggregative precipitation. An extension is then made to account for particle disruption by considering two alternative particle size reduction mechanisms - one representative of particle splitting into two parts of equal volume, the other representative of micro attrition. A comparison is made of the predicted crystallizer PSD performance using the Monte Carlo method with data for both calcium oxalate and calcium carbonate precipitation respectively. Reasonable agreement is demonstrated consistent with crystal agglomeration occurring via aggregation with particle attrition.