Cyathostomins represent a potential cause of equine morbidity and have become the main focus of endoparasite control in managed horses. All grazing horses are at risk of infection with cyathostomins; therefore, the application of appropriate management measures is essential. Anthelmintics currently comprise the main method of control for equine nematodes and the ready availability of these products in some countries has resulted in their use becoming dissociated from veterinary involvement. This is concerning given the levels of anthelmintic resistance that have been recorded in cyathostomin populations. It is important that veterinarians re-establish control over the implementation of parasite control programmes, a major objective of which should be the preservation of anthelmintic efficacy. This article details the principles of cyathostomin control in horses with particular reference to anthelmintic resistance, and the use and interpretation of diagnostic tests for detecting cyathostomins and identifying anthelmintic resistance.