Over the last century in the uplands of Scotland, the extent of heather moorland which supports high densities of mountain hares Lepus timidus has diminished and has gradually been replaced by large-scale commercial forestry plantations or expanding natural woodlands. The potential impact of such a change in land use on host–parasite interactions was investigated by comparing the intensity and prevalence of infection of hares by parasites in two separate habitats: a large hare-fenced young forestry plantation and the adjacent open moorland. Carcasses were collected in November 1990 from within both habitats and after the woodland had been enclosed for nine months. Age, sex, fatness (kidney fat index) and degree of infection of hares were noted. Two parasites were recorded: the nematode Trichostrongylus retortaeformis and the cestode Mosgovoyia pectinata. Clear differences in the intensity of infection of adults occupying the different habitats had occurred in the nine months since woodland enclosure. Adult mountain hares in the woodland had levels of infections approaching four times that observed in hares occupying the open moorland and although not significant, the prevalence of infection was greater in hosts inhabiting the woodland than the open moorland. It is suggested that the parasite–host relationship differs between the two habitats and as heather-dominated moorland landscapes become more fragmented with the increasing establishment of woodlands, the impact of parasites on the life history strategies of mountain hares needs to be reconsidered.