Considering the amount of time students spend in the classroom predominantly in a sitting position, school furniture plays a key role in maintaining and promoting good posture. The aim of the study was to evaluate the mismatch between the existing classroom furniture and students’ anthropometric measures. To assess the mismatch, six furniture dimensions (seat height, seat depth, seat width, upper edge of backrest, sitting desk clearance, desk height) and seven anthropometric measures (popliteal height, thigh thickness, elbow height sitting, shoulder height sitting, subscapular height, hip width, buttock-popliteal length) were measured. A total of 139 students, aged from 14 to 20 (median age = 16), from Slovenian secondary school participated in the study. The highest mismatch was found for seat to desk clearance (98 %), followed by seat width (41 %), seat depth (39 %), seat height (32 %), and desk height (30 %). A higher mismatch was observed in younger students. The results demonstrate a high mismatch between the furniture and students’ anthropometry indicating that a redesign of school furniture in Slovenian high schools is needed. Furthermore, the data obtained could be considered when ergonomically designing school furniture. Studies assessing multiple age groups with larger sample sizes are desired to better understand the student-furniture mismatch.