In order to determine the relative effectiveness of improperly stored, preexposed sensitometric film in the evaluation of processing during a several month period of time, a comparison was made of medical x-ray film which was exposed with a light sensitometer and immediately processed (freshly exposed) and film that had been exposed with a light sensitometer at an earlier time (preexposed) and processed along with the freshly exposed film. The freshly exposed and preexposed films were further divided into a properly stored group, in our darkroom, and an environmentally stored group. The environmentally stored films were kept in a light-tight box in the trunk of a car during the months of August through October, 1983, and August through September, 1984. Each sample set of data included (1) properly stored and freshly exposed film, (2) properly stored and preexposed film, (3) environmentally stored and freshly exposed film; and (4) environmentally stored and preexposed film. A complete set of films was processed at specific times during the study. Initially the time interval for processing between two consecutive sample sets was measured in minutes, with this time interval increasing to hours, days, and weeks. The last sample set was processed 70 days after the study began. Density differences as large as 0.70 between the freshly exposed and preexposed films were observed. A second trial was conducted in order to repeat some of our earlier observations. Two additional film types were incorporated into the second trial. Observations will be discussed along with implications for quality assurance test procedures.