Background: The knowledge on the type and influence of visuospatial ability on sonography performance relevant for ultrasound-guided regional anaesthesia remains incomplete. The aim of this study was to determine whether four different factors of visuospatial ability are important in determining proficiency and procedure time of novices performing brachial plexus sonography. These factors were spatial visualisation, flexibility of closure, spatial relations and speed of closure. Methods: Thirty-three ultrasound novices were recruited in this prospective, observational trial. Five cognitive tests, from a standardised battery that assesses all four visuospatial factors, were administered to each participant at the start of the study. Each novice then performed brachial plexus sonography on a human model at baseline and final exams, separated by a discovery learning session. Novices were examined in their sonography performance by blinded assessors who scored proficiency, technique, image quality, and time taken to perform at both baseline and final scans. Results: Novices with intermediate and high visuospatial ability in spatial visualisation, spatial relations and speed of closure were significantly more proficient and efficient compared with their peers stratified into low-ability cohorts (P < 0.02). The Matrix Reasoning and the Mental Rotations Test-A were both correlated with sonography final exam scores (Spearman rank correlation ρ = 0.38 and 0.36, P = 0.03 and 0.04, respectively). Conclusions: Spatial visualisation, spatial relations and speed of closure, but not flexibility of closure, influence sonography performance. Visuospatial ability testing can identify novices who will require extra assistance in learning ultrasound relevant for regional anaesthesia. (Trial registration: Australian and New Zealand Clinical Trials Registry 12614000819628).