Introduction: Diving is becoming an increasingly popular sport for women. This has created a group of patients with breast implants who practice diving. The purpose of this study was to ascertain i f mammary implants are prone to any change in conformation or structure i f submitted to recreational diving. Material and methods: Severi new implants (Mentor Siltex® Round gel and Siltex® Becker 50 Expander/ Mammary implant; McGhan style 120, 110, 150 and 410) and one undamaged implant removed after two years (McGhan style 410), were submitted to 40 simulated dives in a hyperbaric air compressed facility. Four matching implants were used as a control. Two immersions a day (maximum depth and bottom time of -39 mt and 30 min) were simulated, at controlied temperature (21°C) and humidity (between 60 and 70%). A photograph of ali implants was taken before and after the study. The volume of mammary implants was assessed at sea lcvel before and after each simulated dive by immersing the devices in a closed, water filled container where volume changes were determined by variations of water level in a capillary tube. After each simulated dive, the integrity of the implants was checked. Computerised tomography scan of each implant was done at the end of the protocol to assess variations in gel density, using the Hounsfield unit scale. Results: No implants showed ruptures or variation in volume. Ali implants showed shape alterations, doublé lumen implants showed also irregularity of the inner shell. No alterations of the density could be detected in new implants group. The two-year-old implant showed a hyperdense irregularly ovai shaped profile inside the implant. Conclusions: The tested mammary implants are relatively safe; there were some structural alterations under the test conditions, but not ruptures. U