High Intensity focused Ultrasounds (HIFU) is a novel therapeutic method for local hyperthermia and mechanical action on the tissue. The Ultrasonic waves emitted by a transducer propagate through the skin using a coupling gel to the desired target location. New HIFU transducers have been designed to increase flexibility, efficiency and precision of therapy. They can emits full long lines of 10 mm or more with no gap, but also be electronically steered by altering the phase of the different elements. Generally the extracorporeal therapeutic HIFU used frequencies in the range of 0.8 to 3.5 MHz; it depends of the target and the requirement of the penetration depth. Dermatology and Plastic surgery have innovated in using HIFU combined or not with cold laser to treat under the dermis a precise target the skin laxity or to rebalance the fat volume dispatch on ageing patients. Many studies show safety and efficiency in rejuvenation, skin lifting and fat contouring.