Methods and systems to detect items left in merchandise carriers are disclosed. A disclosed example system includes: an input device configured to receive an indication that a merchandise carrier is to be empty from at least one of a user or a device communicatively coupled to the input device; an overhead imaging device configured to capture an image of the merchandise carrier at a checkout station in response to the indication; an image processor configured to detect based on the image an obscuration of a portion of the merchandise carrier by the presence of an item in the merchandise carrier, and generate an alert signal when the portion of the merchandise carrier is obscured; and an output device configured to receive the alert signal and provide a notification of the presence of the item in the merchandise carrier.