The spectrum of neuromuscular disorders among intensive care unit (ICU) patients has shifted toward disorders acquired within the ICU and away from ''traditional'' neuromuscular disorders that lead to ICU admission. We sought to assess this spectrum by determining the causes and relative frequencies of neuromuscular disorders that led to electromyography (EMG) examinations in our ICU population. Ninety-two patients were studied over a 4 1 β2-year period. Twenty-six (28%) had neuromuscular disorders (mainly Guillain-Barre Β΄syndrome, myopathy, and motor neuron disease) that led to ICU admission. Among patients who developed weakness in the ICU, there was a predominance of organ transplant patients and patients with the systemic inflammatory response syndrome and multiorgan dysfunction. Thirty-nine (42%) developed acute myopathy (consistent with critical illness myopathy in most), and 13% developed acute axonal sensorimotor polyneuropathy (mainly critical illness polyneuropathy). Patients with acute myopathy and acute axonal sensorimotor polyneuropathy had similar functional outcomes. We conclude that among patients who underwent EMG in our ICU population, acute myopathy is three times as common as acute axonal polyneuropathy, and the outcomes from acute myopathy and acute axonal polyneuropathy may be similar.