In surgical staff, low-back pain (LBP) is prevalent and prolonged trunk inclination is hypothesized to be one of its potential causes. The aim of this study was to evaluate the magnitude and duration of trunk inclination in the sagittal plane of surgical assistants during surgical procedures. The three-dimensional trunk orientation was measured in 91 surgical assistants across four medical facilities during surgical procedures using an inertial measurement unit on the thorax. Per participant, Exposure Variation Analysis was used to evaluate the percentage of the total time of trunk inclination (< -10° (backward inclination);​ -10–10° (upright posture);​ 10–20° (light inclination);​ 20–30° (moderate inclination);​ >30° (strong inclination)) taking into account posture duration (< 10 s;​ 10–60 s;​ 60–300 s;​ > 300 s). Participants reported their LBP history and perceived low-back load during the procedure via a questionnaire. Participants were in an upright posture for 75% [63–84%] (median [interquartile range]) of the total surgery time (average surgery time:​ 174 min). Trunk inclination was beyond 20° and 30° for 4.3% [2.1–8.7%] and 1.5% [0.5–3.2%] of the surgery time, respectively. In most of the participants, the duration of trunk inclination beyond 20° or 30° was less than 60 s. Questionnaire response rate was 81%. Persistent or repeated LBP was reported by 49% of respondents, and was unrelated to the exposure to inclined trunk postures. It is concluded that other factors than prolonged trunk inclination, for instance handling of loads or prolonged standing may be causally related to the reported LBP in the investigated population.