A flock of 22-week-old caged layers were presented to a poultry veterinarian for a recent increase in mortality. A presumptive diagnosis of coccidiosis, most likely associated with Eimeria maxima, was made based on history, presentation and gross lesions seen on-site during necropsy. Further investigation revealed that the outbreak was limited to one specific cage-row. Here, the manure belt and scraper system had malfunctioned, leading to a buildup of feces, and potentially giving birds access to an infective dose of coccidian oocysts. Layers on this farm were especially susceptible because, aside from fecal removal (sanitation), no additional control program for coccidia was in place. Resolution of the mechanical malfunction and removal of built-up feces terminated the outbreak, and mortality returned to normal levels. This report highlights the importance of coccidiosis in caged-layers, and reviews the important Eimeria species in poultry, their life cycle, diagnosis and methods of control.