A new protocol for measuring the volume of the entorhinal cortex (EC) from magnetic resonance images (MRI) was developed specifically to measure the EC from oblique coronal sections used in hippocampal volumetric studies. The relative positions of the anatomic landmarks demarcating EC boundaries were transposed from standard coronal sections to oblique ones. The lateral EC border, which is the most controversial among anatomists, was defined in a standard and conservative manner at the medial edge of the collateral sulcus. Two raters measured the EC twice for 78 subjects (healthy aged individuals, very mild AD patients, and elderly patients who did not meet criteria for dementia) to study intra- and inter-rater reproducibility and reliability of measurements. The level of accuracy achieved (coefficients of reproducibility of 1.40-3.86%) and reliability of measurements (intraclass correlation coefficients of 0.959-0.997) indicated that this method provides a feasible tool for measuring the volume of the EC in vivo.