Residual ridge resorption after loss of teeth is a multifactorial oral problem. To examine the association of residual ridge resorption with systemic factors, a cross-sectional study was made of 177 edentulous subjects (43 men and 134 women) aged 76, 81, and 86 years. Resorption in the mandibular and maxillary residual ridges was assessed from panoramic radiographs. The effects on residual ridge resorption of the age, gender, smoking, alcohol intake, body mass index, functioning in daily living, and certain systemic diseases of the subjects were investigated. After adjustment for age and duration of edentulousness, the elderly women had a greater amount of reduction in the mandibular residual ridge than the men (P < 0.001). When the resorption was classified into slight or moderate and severe resorptions, the elderly with asthma were at high risk of severe reduction in the edentulous mandible (odds ratio, 6.0; 95% confidence interval (CI), 1.3-28.2); the elderly women were at high risk of severe resorption in the edentulous mandible, with an odds ratio of 4.5 (95% CI, 1.2-17.1); an inverse association was found between alcohol intake and severe resorption in the edentulous maxilla (odds ratio, 0.4; 95% CI, 0.2-0.9). This study suggests that asthma due to corticosteroid treatment is to be considered a risk indicator for severe resorption of the edentulous mandible, alcohol intake in the elderly may be related to a lesser degree of resorption of the edentulous maxilla. Female gender is confirmed as a major factor resulting in mandibular atrophy.