We examined the demographic, seizure history, personality, and intellectual variables in seizure surgery patients who underwent intraoperative language mapping to identify variables that may help predict inability to cooperate with intraoperative mapping. Of 26 patients who had intraoperative language testing during left hemisphere lobectomy, 9 were unable to cooperate with language mapping procedures. Mapping "failure" consisted of an inability to conform to task demands due to anxiety, inattention, immaturity, or confusion that necessitated changing from local to general endotracheal anesthesia. Patients who were unable to cooperate with intraoperative mapping had significantly lower IQs, lower educational attainment, and higher Depression scale scores on the Minnesota Multiphasic Personality Inventory (MMPI) relative to cooperative patients. There were no statistically significant differences between groups with respect to age, handedness, sex, age of onset of habitual seizures, seizure type, site of seizure focus, presence of a lesion, or previous psychiatric history.