Directed self-guidance, whereby trainees independently practice a skill-set in a structured setting, may be an effective technique for novice training. Currently, however, most evaluation methods require an expert to be present during practice. The study aim was to determine if absolute symmetry error, a clinically important measure that can be assessed by the trainee, is a feasible assessment tool for self-guided learning of suturing skill. Forty-eight undergraduate medical trainees independently practiced suturing and knot tying skills using a benchtop model. Performance on a pretest, posttest, retention test and a transfer test was assessed using (1) the validated final product analysis (FPA), (2) the surgical efficiency score (SES), a combination of the FPA and hand motion analysis and (3) absolute symmetry error, a new measure that assesses the symmetry of the final product. Absolute symmetry error, along with the other objective assessment tools, detected improvements in performance from pretest to posttest (P less than 0.05). A battery of correlation analyses indicated that absolute symmetry error correlates moderately with the FPA and SES. The development of valid, reliable and feasible technical skill assessments is needed to ensure all training centers evaluate trainee performance in a standardized fashion. Measures that do not require the use of experts or computers have potential for widespread use. We suggest that absolute symmetry error is a useful approximation of novices' suturing and knot tying performance. Future research should evaluate whether absolute symmetry error can enhance learning when used as a source of feedback during self-guided practice.