Purpose: To assess the brain core temperature of Alzheimer disease (AD) patients in comparison with healthy volunteers using diffusion-weighted thermometry. Materials and methods: Fourteen AD patients (3 men, 11 women; age range 60–81 years, mean age 73.8 ± 6.1 years) and 14 healthy volunteers, age and sex-matched (mean age 70.1 ± 6.9 years; range 62–84 years; 5 men, 9 women) underwent MR examination between February 2014 and March 2016. MR imaging studies were performed with a 1.5-T MR scanner. Brain core temperature (T: °C) was calculated using the following equation from the diffusion coefficient (D) in the lateral ventricular (LV) cerebrospinal fluid: T = 2256.74/ln (4.39221/D) − 273.15 using a standard DWI single-shot echo-planar pulse sequence (b value 1000 s/mm2). Statistical analysis was performed using a nonparametric Wilcoxon rank-sum test to compare the patient and control groups regarding LV temperatures. Results: There was no significant difference (P = 0.1937) in LV temperature between patients (mean 37.9 ± 1.1 °C, range 35.8–39.2 °C) and control group (38.7 ± 1.4 °C, range 36.9–42.7 °C). Conclusions: Brain core temperature in AD patients showed no significant alterations compared to healthy volunteers.