Technique employing a pressurized fine stream of water (jet) to develop tissue planes or to divide certain soft tissues less traumatically than ordinary sharp dissection. Examples of its use include division of brain and hepatic tissue without destroying smaller blood vessels and other tubular structures. In abdominal surgery, open or laparoscopic hydro-dissection is used to develop tissue planes and separate adhesions. It facilitates dissection of diseased parietal pleura in order to treat malignant pleural effusion. A modification is used in ophthalmological surgery (e.g., phacoemulsification).