Silicon Avalanche photodiodes (APDs) are widely used for detection of visible and near infrared laser radiation. The laser damage of the APD investigated using a Q-switched Nd:YAG laser pulse of 15 ns duration is reported in this paper. Two types of laser damage threshold measurements were performed on the APDs. The minimum flux level of 1064 nm laser radiation resulting in degraded signal-to-noise ration (SNR) is considered the primary type of detector damage. This type of detector damage can be defined in terms of a rearrangement of electrical charge in the semiconductor resulting in increased noise current and therefore poor SNR. The second type of laser damage threshold measurements were performed where the laser power on the detector was increased to the level producing not only a decrease in SNR, but also resulting in visible deformation on the surface of the detector. This type of detector damage can be defined in terms of a rearrangement of some of the atoms of the crystal due to the thermal effects of the laser pulses.