Our aim was to investigate the association between calcium (Ca) intake and number of teeth and tooth loss. The Danish Monica (Monitoring Trends and Determinants in Cardiovascular Disease) study is a prospective observational study from 1982-83 to 1993-94. The study population included 1602 adults (30-60 y) with information on dietary Ca intake and number of teeth and a subset of 511 participants with information on tooth loss from 1987-88 to 1993-94. Ca intake less than the recommendations, estimated by a 7-d food record or a diet history interview in 1982-83, was more frequent among females (55%) than males (45%; P <0.001). Low Ca intake was associated with low number of teeth (1-25 vs. 26-32 teeth) in males [odds ratio (OR) = 1.57 (95% CI = 1.10-2.29)] and females [OR = 1.44 (95% CI = 1.10-2.05)] after adjustment for age, education, smoking, alcohol and sucrose consumption, subjective oral dryness, and time since last dental care visit. The reference group (26-32 teeth) and edentulous participants did not significantly differ. A Ca intake below recommendations was significantly associated with increased risk of subsequent tooth loss in males [incidence-rate ratio = 1.70 (95% CI = 1.15-2.48)]. There was no association in women. Ca intake below recommendations was significantly associated with fewer teeth in both sexes. However, there was a significant, negative association between Ca intake below recommendations and tooth loss in males only. Given the high percentage of individuals with Ca intake below recommendations, consumption of foods rich in Ca should be promoted to preserve oral health.