Alterations in haematological and liver glycogen values during the course ofAncylostoma ceylanicum (100L3, p.o.) infection in hamsters were investigated. In early phase of infection, there were marginal changes in haematological parameters, albuminglobulin ratio and liver glycogen, which transformed into severe alterations on patency (day 18, post infection). Haemoglobin, packed cell volume, total erythrocyte counts and liver glycogen values had a decreasing trend and reticulocytes increased considerably to compensate the red blood cell loss. Albumin/globulin ratio which was in favour of albumin in the beginning, reversed on day 24 p.i. When the animals were deparasitized with mebendazole (5 mg/kgxl, p.o.), all the parameters started resuming normalcy and on day 12 of treatment of all the parameters except albumin/globulin ratio attained the preinfection level.