A novel type of solid-state laser with a tubular active element made of Nd:YAG is presented. Using the tube geometry, one can achieve higher efficiency and higher output power per laser crystal than by using a rod or slab geometry. Our tube laser is pumped from the inside by four flash lamps. The slope efficiency of 9% and the total efficiency of 7.5% at as much as 400 W of output power are, to our knowledge, the highest values reported for flash-lamp-pumped Nd:YAG lasers. At 15 kW, 75% of the maximum available pumping power, the output power is 1000 W. Thermal lensing is five times lower than for an equivalent rod laser.