An ideal drilling system would create a low-pressure region that is limited to the hole bottom while normal or overbalanced conditions are maintained above the bit to control formation fluids. The HydroPulse system shown in Figure 1 provides a means of generating intense cyclic suction pressure pulses that overcome the effects of borehole pressure and increase drilling penetration rate in deep formations. This system would be mounted on a conventional drill string and powered by mud hydraulics. The bottomhole assembly is compact and the system is compatible with downhole motors. The suction pulses could be used to enhance the penetration of conventional roller-cone, PDC or diamond bits. In many situations, such as horizontal drilling, it is difficult to apply a high mechanical thrust to the bit. The hydraulic thrust generated by a suction pressure pulse provides a means of drilling with minimal applied thrust. The suction pulse generator could also be used as a downhole seismic source or for a variety of workover operations such as removal of fines from damaged formations.