Purpose: Assessments of masticatory performance and occlusal force for wearers of obturator prostheses were performed as clinical objective assessments and reported in an earlier study. The purpose of the present study was to evaluate clinically the chewing function of obturator prosthesis wearers by self-evaluations and to examine their relationship to the objective assessments. Materials and Methods: Twenty patients with maxillofacial obturator prostheses who were having a periodic checkup at the maxillofacial rehabilitation clinic in Kyushu University Hospital were recruited for this study. Chewing function was evaluated by 3 assessment tools: a self-assessment mastication scale, a chewing function score, and a mastication score. In addition, correlations among these assessments and objective tests-ie, masticatory performance and maximum occlusal force-were analyzed by the Spearman rank correlation coefficient. Results: The mean self-assessment mastication scale was 63.2 (SD 31.8), the chewing function score was 54.0 (SD 30.2), and the mastication score was 51.4 (SD 33.3). There was no statistically significant relationship between the self-assessment mastication scale and each objective test. However, there were significant correlations between each semisubjective score-the chewing function score and the mastication score-and masticatory performance. There was no relationship between each semisubjective score and maximum occlusal force. Conclusion: A self-assessment mastication scale was not always in agreement with objective assessments, and assessments made by patients should be taken into consideration when arranging maxillofacial rehabilitation. Conversely, both chewing function and mastication scores corresponded with masticatory performance, and these would be useful as screening tests before performing objective tests.