This study aimed to investigate the relationship between missing occlusal units and oral health-related quality of life (OHRQoL) in subjects with shortened dental arches (SDAs). Subjects with SDAs (N = 115) were recruited consecutively from 6 university-based prosthodontic clinics. OHRQoL was measured using the Japanese version of the Oral Health Impact Profile (OHIP-J). An increase of 1 missing occlusal unit was associated with an increase of 2.1 OHIP-J units (95% CI: 0.6-3.5, P = .02) in a linear regression analysis. Missing occlusal units are related to OHRQoL impairment in subjects with SDAs.