Examination of Varroa infestation is important for the diagnosis and evaluation of the efficacy of methods and substances used for the control of varroasis. The aim of the study was to estimate the accuracy of the method of examining samples of adult bees to determine the Varroa rate of infestation in the colony. The experiment was carried out on 10 bee colonies. From each of them 7-8 samples of 200-300 adult bees were taken by chance and examined. Bees and Varroa mites in the sample were counted. The mean rate of infestation, standard deviation and coefficient of variation were calculated for each colony and for the method. The obtained results show that especially in colonies highly infested with mites the results of the rate of Varroa infestation are quite varied. By the used method the mean error of the examination of Varroa infestation was 28.8%. The examination of single samples of 200-300 adult bees is not precise and the results should be taken as an approximation.