A new type of analysis of the electromyographic spike obtained from the full interference pattern of extraocular muscles is introduced. It entails the use of a computer for the measurement and statistical analysis of the duration of onset-to-onset from one spike to the next one and the onset-to-onset immediately preceding it. The lateral, medial and superior recti muscles were examined in 13 subjects, of whom 7 were healthy, 3 were suffering from ocular myopathy and 3 from infranuclear neuropathy. Sharp, well-defined differences between healthy, myopathic and neuropathic lesions were found. The technique is simple, rapid and accurate. Its value is enhanced by the fact that no area of overlap was encountered between the 3 basic types of muscle examined. The parameter, and its statistical analysis, appears to be an additional and reliable tool in the interpretation of electromyography (EMG), especially of value in subclinical, incipient or doubtful clinical conditions involving eyeball motility.