Background: We studied a visual artist with Lewy body dementia (LBD) to learn how this disease influenced his paintings during the course of the disease. Methods: Study 1 evaluated two paintings of the same subject matter, one that the patient painted before his illness and the other after the onset of this disease. Study 2 evaluated a collection of his paintings from the time before he was ill (1994) until the time he stopped painting when he was suffering with LBD (2002). To learn how the onset and progression of LBD affected his paintings we had judges score the following qualities: aesthetic-beauty, closure completeness, evocative impact, novelty, technique and representational quality. Results: In Study 1 we found that the representational ratings for the picture he painted when he had LBD was significantly lower than the picture he painted before he developed LBD. In Study 2, we found that all the artistic qualities measures temporally declined except novelty. We also found that the paintings that were judges as having the highest quality representations were significantly more novel than those that had poorer representations. In addition, we conducted a forward stepwise regression analysis using quality measures as predictor of year. This analysis revealed that only representational quality significantly predicted painting year. Conclusions: Our results suggest that as LBD progresses, except for novelty there is a gradual degradation of the ability to visually express artistic subject matter. It possible that the preserved ability to paint novel picture is related to relative preservation of frontal lobe function, but the degradation of other artistic qualities might be related to deterioration of the parietal lobes which either impairs the brain's iconic representations or the knowledge needed to portray these representations.