OBJECTIVE : We aimed to clarify the impact of the apparent diffusion coefficient (ADC) value of the mesorectum from preoperative magnetic resonance imaging (MRI) on surgical difficulty in laparoscopic anterior resection (Lap-AR) for rectal cancer. METHODS : In total, 67 patients who had undergone curative Lap-AR for rectal cancer in our hospital from January 2008 to March 2015 and had preoperative MRI findings available were included. We randomly calculated the average ADC in three regions of the mesorectum at the level of the upper edge of the superior border of the femur. Univariate and multivariate analyses were performed to evaluate the correlation between the patients' clinicopathological characteristics, including the ADC value and short-term surgical outcomes. RESULTS : The univariate analysis revealed that a lower ADC value was associated with a significantly increased operative blood loss (p = 0.008) and prolonged operative time (p < 0.001). The multivariate analysis adjusted for the body mass index, anal verge, tumor location, covering stoma, clinical T factor and conversion revealed that the ADC value was an independent risk factor for a prolonged operative time (R2 = 0.6003, p < 0.001). Furthermore, the multivariate analysis adjusted for the body mass index, anal verge, covering stoma, clinical T factor and conversion revealed that the ADC value was an independent risk factor for an increased blood loss (R2 = 0.4345, p = 0.008). CONCLUSIONS : A lower ADC value of the mesorectum might be a predictor of surgical difficulty in Lap-AR for rectal cancer.