The operation and characteristics of liquid lasers with a purely organic medium are described. A giant‐pulse ruby laser is used to pump solutions of organic dyes in various organic solvents in concentrations ranging from 10−3to 10−6moles/liter. The solutions are contained in plane‐parallel cuvettes acting as laser cavities. Wavelengths from 730 to 870 nm, megawatt peak powers and beam divergence angles of 5 mrad have been observed. The laser wavelength of each dye is tunable over a great part of its fluorescence band, e.g. by a change in concentration.