OBJECTIVE This cross-sectional study analyzes how bone resorption affects the masticatory function and investigates the relation between perceived and measured masticatory function. METHODS Thirty complete dentures wearers were divided in two groups according to mandible bone atrophy based on the classification criteria from Cawood & Howell. Retention and stability of the mandibular complete denture, masticatory performance (MP) indexes (X_50 and B) and masticatory efficiency (ME, sieves 4 and 2.8) were evaluated. Geriatric Oral Health Assessment Index (GOHAI) and Dental Impact on Daily Living (DIDL) questionnaires were completed by the patients. RESULTS A strong correlation between bone atrophy and poor retention was found (P=0.0132). Neither masticatory performance indexes nor GOHAI and DIDL domains showed statistical differences (P>0.05) when patients were compared according to the atrophy criteria. Mandibular length showed a negative correlation with ME4, showing a positive association (R2=0.17, β=-0.67, P=0.029). Mandibular denture retention was significantly correlated with MPB (P=0.01) and ME2.8 (P=0.01). GOHAI showed a positive association between the physical and the functional domains and ME2.8 (R2=0.17; β=1.22; P=0.02). DIDL showed a negative association between ME4 and oral comfort domain (R2=0.16; β=-2.94; P=0.02). CONCLUSIONS Mandibular bone height does not directly affect the masticatory function and is inversely correlated with the self-perceived masticatory ability.