Background and Purpose: The aim of this study was to evaluate whether poor oral hygiene is associated with the intima-media thickness of the carotid arteries, which is one of the predictors of future progression of subclinical atherosclerosis. Methods: We selected 108 patients during periodontal examinations according to their oral hygiene. The patients had no history of atherosclerotic disease. The results of carotid artery B-mode ultrasonography examinations were analyzed at baseline and after a mean of 7.8 months. Patients were scored on the DMFT index for the number of decayed (D), missing (M), and filled (F) teeth (T). We also used the Silness-Loe plaque index (SLI) to evaluate oral hygiene and dental plaque. The patients were divided into 2 groups according to DMFT and SLI criteria. Group I had a DMFT index of 0 to 3 and an SLI score of 0 or 1; group II had a DMFT index of 4 to 28 and an SLI score of 2 or 3. Results: Dental status and oral hygiene were significantly associated with carotid artery intima-media thickness. Patients with increasing DMFT and SLI indices were correlated with intima-media thickness of the carotid artery. Conclusions: Chronic poor oral hygiene and tooth loss are related to subclinical atherosclerotic changes in the carotid arteries and might be indicative of future progression of atherosclerosis.