This paper documents the medicinal plants used to treat endoparasites and stomach problems in dogs, cats and pigs in British Columbia, Canada. Ethnoveterinary data was collected over a 6-month period in 2003. The majority of the information on pets came from 2 naturopaths, 10 herbalists, 5 dog trainers, breeders and pet shop owners, 9 holistic veterinarians and 6 of 27 organic farmers. Two pig farmers joined the study in the final stages. The following plants were used as anthelmintics: Artemisia cina O. Berg and C.F. Schmidt, Artemisia vulgaris L., Artemisia annua, Calendula officinalis L., Echinacea purpurea (L.) Moench (all Asteraceae), Mentha piperita L. and Salvia officinalis L. (Lamiaceae) (Allium sativum L. (Alliaceae), Cucurbita pepo L. (Cucurbitaceae), Eugenia caryophyllata Thunb (Myrtaceae), Gentiana lutea L. (Gentianaceae), Hydrastis canadensis L. (Ranunculaceae), Juglans nigra L. (Juglandaceae), Olea europaea L. (Oleaceae) and Ruta graveolens L. (Rutaceae)). Stomach problems were treated with: Achillea millefolium L. (Asteraceae), Aloe vera (L.) Burm. f. (Asphodelaceae), Elytrigia repens (L.) Desv. ex Nevski (Poaceae), Frangula purshiana (DC.) Cooper (Rhamnaceae), Juniperus communis L. (Cupressaceae), Melissa officinalis L. and M. piperita L. (Lamiaceae), Petroselinum crispum L. (Apiaceae), Plantago major L. and Plantago ovata Forssk. (Plantaginaceae) Rumex crispus L. and Rumex obtusifolius L. (Polygonaceae), Ulmus fulva Michx. (Ulmaceae) and Zingiber officinalis Roscoe (Zingiberaceae). There is insufficient information available to assess the anthelmintic efficacies of C. officinalis, Salvia officinalis, Eugenia caryophyllata and O. europaea; the other plants have mid- to high-level validity for their ethnoveterinary uses.