Introduction: We assessed the predictive value of electrophysiological tests as a marker of clinical disease onset and survival in superoxide‐dismutase 1 (SOD1)^G93A mice. Methods: We evaluated the accuracy of electrophysiological tests in differentiating transgenic versus wild‐type mice. We made a correlation analysis of electrophysiological parameters and the onset of symptoms, survival, and number of spinal motoneurons. Results: Presymptomatic electrophysiological tests show great accuracy in differentiating transgenic versus wild‐type mice, with the most sensitive parameter being the tibialis anterior compound muscle action potential (CMAP) amplitude. The CMAP amplitude at age 10 weeks correlated significantly with clinical disease onset and survival. Electrophysiological tests increased their survival prediction accuracy when evaluated at later stages of the disease and also predicted the amount of lumbar spinal motoneuron preservation. Conclusions: Electrophysiological tests predict clinical disease onset, survival, and spinal motoneuron preservation in SOD1^G93A mice. This is a methodological improvement for preclinical studies. Muscle Nerve 50: 943–949, 2014