Twenty-six first season calves were allocated into four groups which were turned out on May 21 to graze separate permanent pastures. One group (group A) remained untreated. The others were treated each month with albendazole either as an oral drench (group B) through supplementary feed (group C) or through the drinking water (group D). Neither clinical disease nor weight gain depressions were observed in any group. Although the infection levels were low, the faecal excretion of trichostrongylus eggs, the serum pepsinogen activities and the pasture larval contamination all indicated a marked reduction in the levels of infection of groups B, C and D. The serum pepsinogen activities of groups B and C were similar and remained below 1 unit of tyrosine/litre of serum whereas that of group D was intermediate between these two groups and group A. The labour saving principle which was applied to group C is recommended under conditions similar to those of the present experiment.