Anticoccidial drug resistance in coccidia has been known since the 1960s, and experimental selection for resistance in the laboratory has been done for most available products. However, routine testing for sensitivity in field isolates has only begun in recent years. Poultry producers are faced with greater challenges because of consumer preferences for ‘antibiotic-free’ products and a lack of new products for disease control. The classification of some of our most effective anticoccidials as ‘antibiotics’ has severely limited their use, causing us to rely on older products that are prone to resistance development. The interaction between coccidiosis and other diseases such as necrotic enteritis places more importance on routine testing for drug sensitivity. In this review, we have summarized the use of the anticoccidial sensitivity test (AST) as it is conducted and interpreted by poultry health specialists.