Laser treatment of tissues can generate elevated pressures in the kilobar range. This review will provide an overview of the known cellular and biochemical effects of elevated pressure. As an example of pressure effects on enzyme structure/function. I will present results on the effects of high pressure on the stability and activity of the enzyme DNA gyrase. Information will also be provided on the pressure shock response of the bacterium Escherichia coli to abrupt shifts in elevated hydrostatic pressure. Finally, I will describe an unusual group of organisms which have evolved specialized adaptations for life at high pressure. These are the deep-sea barophilic ('pressure loving') bacteria.