In order to investigate the effect of hydrostatic pressure on the fatigue crack growth behaviour of solid polymers, an apparatus was designed for maximum pressure of 3000 kgf cm(-2). The. crack growth rates as a function of stress intensity factor range, Delta K, were measured using compact tension specimens of polycarbonate under pressures of 1-2000 kgf cm(-2). It was shown that (1) the fatigue crack growth rates at pressures higher than 500 kg cm(-2) were nearly insensitive to hydrostatic pressure, (2) the slope on a log(dc/dN) versus log (Delta K) diagram was higher at the high pressures than at an atmospheric pressure, and (3) shear lips and the tear lines appeared on the fracture surfaces at atmospheric pressure, while they were not observed at pressures higher than 500 kgf cm(-2).