The diagnosis and treatment of a case of crimidine poisoning in a dog are described. Presenting signs were seizures and vomiting. The vomitus contained a purple coloured cereal grain. The signs and grain colour were suggestive for a rodenticide with convulsive effects The diagnosis of crimidine poisoning was made by thin layer chromatography and was later confirmed by finding the source of the poison. Except for the administration of Vit B6, the specific antidote for crimidine, general treatment principles for poisoning were followed. The treatment of crimidine poisoning is time consuming and requires intensive care facilities.