A prospective study for the noninvasive diagnosis of malignant hyperthermia (MH) susceptibility was conducted in 30 patients using 31P magnetic resonance spectroscopy (MRS). A score of MRS muscle abnormalities was determined before the in vitro contracture test. The patients were classified as MH susceptible or MH negative, according to an algorithm of MRS score values. Twenty-three patients were correctly classified using the MRS test, five had inclusive MRS score values and two patients were false-positive. There were no false-negative patients. These preliminary results suggest that the MRS test could be useful as a possible noninvasive diagnostic test in MH susceptibility.