Considering that the analysis of total gut contents in large sized bivalve species is extremely time-consuming, the aim of the present study is to give a statistically tested methodology that permits quantitative assessment of gut contents in bivalves from selected subsamples. Thirty Patagonian scallops Zygochlamys patagonica (35–55 mm total height) from Reclutas bed (39° S to 55° W) were dissected. The complex “gut digestive gland” was extracted for the analysis of approximately 1/6 of the total content. This procedure was analyzed using the results of the 2-stage sampling theory. The error in the estimation of the mean number of particles per gut was estimated between 15% and 16% using this methodology.