Provided are a medical image processing device, an endoscope system, and a method of operating a medical image processing device that can enhance the reliability for recognition results obtained by recognition processing in a case where a lesioned part or the like is diagnosed by recognition processing of artificial intelligence (AI). Comparison between a first medical image (80) and a second medical image to be a comparison target with respect to the first medical image (80) is performed. A specific medical image (82) selected in accordance with a result of the comparison from among the second medical images is acquired. A monitor displays a plurality of recognition results (84) that are obtained from recognition processing that is performed with respect to the specific medical image (82) and performed for recognizing the observation target.
