Background: Diversity of healthcare personnel has been associated with improved care of diverse populations. To determine whether neurosurgical clinical trialists were as diverse as the populations they treated, we investigated the sex/gender and race/ethnicity of participants and compared them to authors of randomized controlled trials (RCTs) in neurosurgery, orthopedic surgery, general surgery and plastic surgery. Methods: Embase and MEDLINE were systematically searched from 2001 to 2021. RCTs were limited by impact factor and selected using a series technique. Data on author and trial characteristics were extracted independently and in duplicate, and compared for each speciality. Results: 1548 articles were included. Interim analysis revealed the mean proportion of women authors was lowest in neurosurgery (5%) and highest in plastic surgery (50%). Trialists that were most reflective of their participants sex/gender were general surgery (42% authors vs 46% participants) and plastic surgery (50% authors vs 66% participants). 94% of RCTs did not report participants’ race/ethnicity. No RCTs excluded participants based on sex/gender or race/ethnicity. Conclusions: Compared to other surgical fields, neurosurgery had the poorest correlation of author sex/gender with the population being studied. Efforts are needed to improve the diversity of neurosurgical trialists, access to RCTs for underrepresented groups and standardized reporting of participants’ race/ethnicity.