The aim of this study was to determine the risk factors influencing the occurrence of parasitic infections in organic sheep farms in Germany. Therefore, 635 pooled faecal samples from sheep kept on 20 organic farms were collected and examined by standard parasitological analyses for gastrointestinal nematodes (GINs), Eimeria species (spp.) and liver flukes (Fasciola hepatica). Additionally, 128 double-pooled samples were analysed for lungworm larvae. In 60.5% of all samples, parasite stadiums were detected, and 38.3% of the double-pooled samples were lungworm-positive. Production period, months and year of sampling had significant effects on infections with GINs (p < 0.05). The prevalence of GIN infection was lowest in 'dairy'(40.0%) when compared with'meat'sheep (65.4%). The odds of being infected with Eimeria spp. was influenced by the month (p < 0.05). The number of ewes on a farm, the primary purpose or the grazing area showed no significant effects. Infections with lungworms occurred in tendency more often 'after' lambing period.