BACKGROUND: Controversy persists as to whether round or anatomical form-stable breast implants provide the most aesthetically pleasing results, and there is a paucity of evidence comparing cosmetic outcomes of these two implants. A blinded study comparing aesthetic outcomes was conducted in an attempt to address this issue. OBJECTIVES: The authors compare aesthetic outcomes between round and anatomical form-stable breast implants. METHODS: Pre- and postoperative photographs of 60 consecutive patients undergoing breast augmentation (33 round, 27 anatomical) by a single surgeon were reviewed by 22 plastic surgeons. Photographs were graded on a modified Likert scale (1, poor; 4, excellent) for overall aesthetic result, upper pole contour, and natural appearance. The panel was asked to determine implant shape. RESULTS: Anatomical implants scored higher for upper pole contour: anatomical 2.80 (±0.44 - standard deviation) vs round 2.60 (±0.38). With regard to natural appearance and overall aesthetic results, anatomical implants scored higher: 2.89 (±0.42) vs 2.56 (±0.36) and 2.86 (±0.41) vs 2.72 (±0.37), respectively. None of these differences achieved statistical significance, and 62.7% of round and 49% of anatomical implants were correctly identified. There was no significant difference in the body mass index (BMI) between the 2 groups (P = .21). CONCLUSIONS: No significant difference (P > .05) in the general and specific cosmetic points between round and anatomical implants was demonstrated; many on the panel were unable to identify implant shape correctly. Both techniques seem to yield good cosmetic results. Clearly the decision on which implant to use must be made on an individual patient basis because many factors influence overall aesthetic outcome. Anatomical implants should not be assumed to produce a more natural result. LEVEL OF EVIDENCE: 4 Therapeutic.