The goal of this study was to define the incidence of double breast contour in primary aesthetic breast augmentation and to analyze its risk factors. An independent plastic surgeon analyzed the data of 200 patients who had a primary aesthetic breast augmentation with silicone gel implant and with a minimum 12-month follow-up. All patients had pre and postoperative standardized photography. Mastopexy-augmentations, breast reconstructions, breast malformations (tuberous breasts and Poland syndrome), and patients with incomplete data were excluded from the study. Assessment was achieved using an original standardized evaluation form (preoperative breast morphology, surgical options, postoperative aesthetic results). Patients were also asked to complete an exhaustive satisfaction form. A double breast contour was assessed clinically using Massiha's classification. The mean follow-up was 36 months. The double breast contour incidence was 7%. All of them were type I (the so called waterfall deformity). There was no type II (double inframammary crease). They were minor for 6.5% and major for 0.5%. They were related to a preoperative breast ptosis, subpectoral placement, and implant upper malposition. The rate of the type I was 10.5% of submuscular augmentation and 15% of preoperative breast ptosis. A double breast contour was primitive for 6% and secondary for 1% (pregnancy and breast-feeding postaugmentation). It was bilateral for 4.5% (3 cases of upper malposition, 1 case of medial malposition, 2 cases of pregnancy with breast-feeding postaugmentation and 1 patient refused a mastopexy-augmentation). It was unilateral for 2.5% related to a preoperative breast asymmetry with ptosis asymmetry and skin quality asymmetry. The satisfaction rate in the group "double contour" (14 patients) was 85.7% (vs. 91.9%). One patient had revision surgery (upper malposition). These types of deformities are fundamentally different with consideration on their clinical aspects, physiopathogeny, prevention and treatment. Type I major risk factor is subpectoral augmentation of ptotic breasts (with medium to bad skin quality and loses muscle to gland attachments). The muscle at the inferior pole of the breast is a "brake" preventing implant to fill the envelope. This risk is increased with implant malposition, constitutional ptosis asymmetry with symmetrical implant placement and selection of an insufficient implant projection or dimensions. This deformity can be avoided with selection of a subglandular or dual plane (type II or III) placement, a sufficient implant volume or projection and anatomic prosthesis. Type II is related to a lowering of a well-defined submammary fold more commonly in constricted and dens glandular breasts. This deformity can be avoided with respecting the inframammary fold, radial incisions on the gland's posterior surface, and selection of anatomic implants.