Purpose: This study investigated the reliability of visual assessment of marginal gaps in relation to the use of magnification and the operator's profession. Materials and Methods: A titanium bar was notched, simulating 40 marginal gaps, and 35 operators performed a quantitative evaluation of the incisions. Results: Visual examination was neither sensitive nor specific, as an extreme variability of data was recorded. The precision of readers improved with magnification aids only for clinicians; technicians were significantly more accurate in evaluating the incision's width. Conclusion: The visual examinations were inadequate to decide the clinical acceptability of a restoration with regard to its marginal fit. Int J Prosthodont 2014;27:161-164. doi: 10.11607/ijp.3649