The present technology relates to an image processing device, an image processing method, a program, and an endoscope system that can reduce a burden on a user. A parallax amount adjustment unit adjusts the parallax amount of a three-dimensional (3D) biological image of an imaged living organism, depending on whether the parallax of the 3D biological image puts a burden on a user. The present technology can be applied to an endoscope system or the like that captures an image of a living organism with an endoscope, for example.