Temporally incoherent twin beams of light are generated by means of an optical parametric amplifier that is pumped by the second harmonic of a Q-switched multi-longitudinal-mode Nd:YAG laser. For a parametric gain of 1.12, the intensity nose levels on the direct-detected signal and idler twin beams are found to be correlated by 1.4 dB, whereas the subtracted noise falls below the quantum limit by 0.7 ± 0.1 dB (15%). Although no direct coherence experiment is performed on the twin beams themselves, their temporal incoherence is manifested by the stringent path-length matching requirement between the pump and input signal beams.