Several small cryogenic pumps for a liquid rocket engine have been made and tested. These pumps have a small impeller and are characterized by high speed and high head. The main design characteristics of these pumps are as follows: stage specific speeds of 80∼200 (m, m3/min., rpm), flow rates of 16∼52.5 L/s, pressure rised of 4.9∼26.0 Mpa, rotating speeds of 16, 500∼80, 000 rpm and impeller diameters of 83∼146 mm. The present test pumps showed higher efficiency even in the range of small stage specific speeds than previously reported. Furthermore, the two-stage pumps showed considerably higher efficiency than the single-stage pumps with the same stage specific speed. Remarkable improvement of suction performance owing to thermodynamic effects of cavitation was also confirmed regarding the present small high speed pumps. With regard to pump efficiency measurement, the adiabatic efficiency relative to cryogenic pump fluids was investigated and a considerably good agreement between it and the actual pump efficiency was recognized.