Measurements of laser-stimulated action potentials in the sciatic nerve of leopard frogs (Rana pipiens) are made using two infrared lasers. The dorsal sides of the frog’s hind limbs are exposed to short-pulsed 1540- and wavelengths at three separate spot sizes: 2, 3, and . Energy density thresholds are determined for eliciting an action potential at each experimental condition. Results from these exposures show similar evoked potential thresholds for both wavelengths. The -diam spot sizes yield action potentials at radiant exposure levels almost double that seen with larger beam sizes.