There exists a reciprocal relationship between oral health and body mass index (BMI), with the latter reflecting the nutritional status of elderly individuals. However, the relative importance of oral health versus that of nutritional status in government-institutionalized elderlies in Jakarta remains unclear. The present study aimed to evaluate the relationship between the number of remaining teeth (NRT), the number of occlusal pairs (OP), the presence of oral lesions, and BMI in institutionalized elderlies. It is a cross-sectional study with consecutive sample of 231 elderlies (90 males and 141 females) aged ≥60 years residing at institutions in Jakarta. A questionnaire was employed to collect sociodemographic and behavioral data on the study group. BMI was determined based on weight and height data. The NRT, OP, and the presence of oral lesions causing painful sensations were observed and recorded. Logistic regression analysis was used to evaluate the risk factors contributing to an inadequate BMI. The percentage of edentate respondents was higher in the underweight group (31.5%) than in the normal or overweight groups (17.8% and 21.2%, respectively). Percentage of respondents without occlusal pairs was high (58,9%). The types of oral lesions found were ulcerations, abscesses, and atrophic tongue. Underweight elderlies tended to present with more oral ulcerations and abscesses (11.2% and 4.5%, respectively). Edentulousness and present of systemic complaints were the factors influencing underweight condition in this population. This study shows that edentulousness had influence on the underweight condition, while the number of occlusal pairs and present of oral lesions had shown no influence on BMI. It is important to retain suggested number of teeth in increasing the chance of having an adequate body mass index in this population. © 2019 Journal of International Dental and Medical Research.