The statistical evaluation of the results obtained by kymographic registration of antihelminthic action on the isolated helminth preparation is discussed. The statistical unit was assumed to be a mean reaction magnitude expressed by the surface (calculated planimetrically) limited by the kymographic curve. divided by the length of the time segment. The results should be given in terms of concentrations leading to 50% of maximal reaction to standard drug; the concentrations are calculated by means of regression equatiom or graphically. A method for calculation of standard concentration error is given. A „universal" topologic test is recommended for the evaluation of results which fail to fulfill the requirements of Student's test. The importance of the coefficient B from the straight regression equation as a measure of action rate of antihelminthic drug is stressed.