Quality control procedures of implant manufacturers are of concern to the profession, as a number of companies claim that their components are interchangeable with those of competitive systems. The external hex dimensions of six implant systems were measured and the ranges and coefficients of variance determined. Smaller ranges and coefficients of variance suggest better quality control. The results indicated a considerable difference in the quality control at implant manufacturing companies. (Implant Dent 1994;3:51–53)