Obesity has been associated with several chronic diseases, such as coronary heart disease, stroke, adverse pregnancy outcomes, diabetes, and mortality; however it has not been until recently that an increased body mass index (BMI) was also related to dental health, especially periodontitis. We conducted a research to determine whether oral health was related to BMI using a cross-sectional design. Of 320 non-smoking subjects aged 31–60 years recruited from the patients referred to Dental Clinic at the Clinical Hospital Center in Rijeka, Croatia, a detailed dental health status was completed for 292 subjects. Measurements of weight and height, education level and frequency of toothbrushing were also recorded. Dental index comprising information on caries, periodontitis, periapical lesions, and missing teeth was used as a measure of dental health. Dental index and education level both correlated significantly with BMI, however for the dental index this correlation was rather weak. The same could not be proven for the frequency of tooth brushing. Multivariate linear analysis showed that BMI was most dependent upon the number of missing teeth (88.6%), followed by the number of carious lesions (8.3%). Persons with an increased BMI had slightly worse dental health, as represented by higher dental index, regardless of their toothbrushing routines, and lower levels of education. Prevention programs should aim at rising both the general health awareness and improving oral health.