The present study was performed to evaluate thein vivoefficiency ofCurcurbita pepo(pumpkin) seeds,Cymbopogon citratus(lemongrass) essential oil andPlantago lanceolata(ripleaf) leaves against helminth infections in laying hens. In the first experiment, 75 Lohmann LSL Classic hens naturally infected withAscaridia galliwere assigned to groups of five; groups were randomly assigned to one of three treatments with five replicates each (untreated control; lemongrass oil: 1 g/bird/day; pumpkin seeds: 10 g/bird/day). Feed consumption and egg production were continuously recorded, individual faecal egg counts were determined weekly, andE. coliandLactobacillusspp. three times during the experimental period of 29 days. After slaughter, intestinal worms were counted and sexed. Pumpkin improved feed conversion as compared to the control (p= 0.008) and to lemongrass (p= 0.021); no treatment effect on any other parameter was found.In the second experiment, 75 LSL pullets were artificially infected with 3 × 200A. gallieggs, randomly divided into groups of five and assigned to one of three treatments (untreated control, lemongrass oil: 1 g/bird/day; ripleaf: 5% of ration). After 109 days of sampling as described above, hens were slaughtered and worm burdens determined. Performance of the animals did not change regardless of the treatment and none of the treatments resulted in changes of the microbiological and parasitological parameters. In conclusion, with the exception of improved feed conversion in the pumpkin group, no positive nor negative effects of the additives on performance, parasitological and microbiological parameters of naturally and artificiallyA. galliinfected laying hens were observed.