Purpose: Recently, cone beam computed tomography (CBCT) was developed and applied to presurgical imaging for dental implant treatment. Because the values obtained from CBCT images are not absolute values, unlike the Hounsfield units obtained by medical CT, the relationship between the values of trabecular bone morphometry obtained in small-volume CBCT images and CT values obtained from multislice CT was evaluated in an in vitro study. Materials and Methods: Small-volume CBCT and multislice CT were performed in the posterior mandible. Subsequently, morphometric analysis of the trabecular bone in CBCT images was performed using three-dimensional bone morphometry software, and the correlations between the trabecular bone volume per total tissue volume (BV/TV) obtained using CBCT images and CT values generated from multislice CT images were analyzed. Results: BV/TV ranged from 3.1% to 42.7%, with a mean of 20.4% (SD: 11.4) when the setting was 0.5 for the threshold. The correlations between BV/TV using the threshold values ranged from 0.3 to 0.7, and CT values showed a high level of correlation (range: 0.83 to 0.93). Conclusions: The trabecular BV/TV was closely correlated with CT values obtained using multislice CT images. It was suggested that the trabecular BV/TV can be used to evaluate the density of mandibular cancellous bone in dental implant treatment. Keywords: cone beam computed tomography, dental implant, mandible, morphometric analysis, trabecular bone