A method for determining the biological activity of embryonated Trichuris eggs is described, in which at least one of the following determinations is carried out: a) Determination and/or confirmation of the stage of the embryonal development of helminth eggs with the aid of quantitative PCR analysis by using suitable marker sequences for ascertaining the copy number of the genomic DNA, b) Determination of the metabolic activity of embryonated helminth eggs by means of biochemical and/or molecular biological methods, c) Determination of the inducibility of gene expression in embryonated helminth eggs, d) Microscopic determination of the motility of helminth larvae in the egg over long periods of observation after pre-incubation at increased temperatures and/or e) Determination of the hatching rate of Trichuris larvae in a laboratory animal, wherein the intact embryonated eggs recovered from the contents of the intestine are quantified compared to an internal standard.