Abstract: An inclinometer (I) for attachment to a radiographic film cassette (C) for indicating on radiographic film in the cassette the angular orientation of the film during exposure. A cylindrical body (10) defines therein an array of cylindrical passages (12) having axes each orthogonal to the body cylinder axis. Each passage axis has a rotational orientation about the body axis which differs by approximately 10 degrees from that of its respective neighbors. A radiopaque spherical indicator element (14) is disposed within each respective column for gravity responsive movement as a function of angular orientation of the body structure. Clamping means (20, 22) holds the body structure superimposed over a portion of radiographic film to be exposed. The relative positions of the indicator elements within their respective passages appears on the exposed film, indicating the angular disposition of the film during exposure.