Anthelmintic resistance within nematodes has become a very common issue, however, the data about its
occurrence in the gastrointestinal nematodes of sheep in Poland are very limited. This study was carried out in order to
evaluate the presence of benzimidazole resistance in highly pathogenic Haemonchus contortus by means of
parasitological and molecular techniques. The research represents the first Polish attempt to confirm the presence of a
mutation at codon 200 of the β-tubulin isotype 1 gene in H. contortus by PCR-RFLP. The occurrence of this mutation
indicates the risk of ineffective benzimidazole treatment, nowadays commonly used for parasite control in Poland. The
resistant parasites were detected by means of FECRT in a sheep flock (30 individuals) from southern Poland. To
confirm the resistance on the molecular level, primers designed according to the sequences available in Genebank were
used to detect the mutation. Unfortunately, as the PCR product was shorter than required (403 bp), further analyses are
needed. The obtained results may indicate the high variability within the parasite population. Hence, it is essential to
adapt the reaction conditions to our geographic strain of the nematode – and further analyses are required