Aim: To determine the repeatability of mastoid process measurement on dry bone and MCST scans. Methods: The measurement was performed by one person, and it was carried out in the laboratory for forensic and biological anthropology of the University of Split, twice, with a time gap of two days. Measurements were made using the guidelines from the Standard Methods for Data Collection Procedures for Forensic Skeletal Material 2.0 manual, in which the length of the mastoid process is defined as the distance from the porion (po) (upper point on the external auditory canal) to the mastoid (ms) (the lowest point on the mastoid process). Measurements of the right mastoid process were performed on thirty skulls from the osteological collection from the University Department of Forensic Sciences. The measurement was made on dry bone with the help of a caliper, and the mastoid process on MSCT images, from the University's virtual database, was measured using Stratovan, Software Version 2020.10.13.0859 (Stratovan Corporation, Davis, CA). The repeatability of the test measurement is based on the calculation technique of the relative technical error of measurement (rTEM) set at ≤ 1.5%, and a reliability coefficient of 0.95. Results: After the statistical data analysis, the following values were obtained: technical error of measurement (TEM) in the range of 1.57-1.97 mm, which is more than the allowed 1.5 mm, relative technical error of measurement (rTEM) in the range of 4.86-6.00 %, which is an unacceptable level of intra-observer error because it should be ≤ 1.5 %, and a reliability coefficient (R) in the range of 0.59-0.77 which result is not satisfactory because its value ranges are from 0 (not reliable) to 1 (complete reliability), and in this study was chosen the reliability coefficient of 0.95. Conclusions: Measuring the mastoid process requires anthropological experience and a good previous knowledge of skull anatomy, as well as continuous work on measuring skeletal remains to achieve skills. For measurements on MSCT images, the measurer should undergo certain training in radiological data processing. The repeatability of the measurement of the mastoid process is conditioned by the experience and expertise of the measurer because it is very complex to analyze due to its anatomical structure.