Relationship between faecal egg counts and haematological parameters: PCVs, peripheral eosinophil counts, total white blood cell counts (TWBCs) and white cells composition in blood of Polish Wrzosowka breed of sheep were estimated in 1995 and 1996. Hoggets were naturally infected with gastrointestinal nematodes. Anthelmintics were not used. Among Teladorsagia circumcincta, Cooperia spp., Chabertia ovina, Nematodirus spp. (mainly N. spathiger) two species: Trichostrongylus spp. and Haemonchus contortus dominated. High repeatability of EPGs, PVCs and peripheral eosinophil counts were observed over two grazing seasons. There were no significant changes in TWBCs, in percentage of lymphocytes and neutrophils in blood smears. Marked differences in percentage of eosinophils in blood smears were confirmed in peripheral eosinophil counts. Additionally, the eosinophil counts in most sampling data correlated negatively with EPGs. The lowest level of haematocrit correlated negatively with EPGs when the highest percentage of L3 H. contortus larvae were found in the faecal culture. The results reveal that EPGs, PVCs and peripheral eosinophil counts could be considered in terms of phenotypic markers for identification of Wrzosowka sheep with different level of acquired immunity to natural trichostrongylid infection.