The M Test, a brief test for measuring malingering of schizophrenic illness, contains true-false items describing actual symptoms of schizophrenia, bizarre attitudes and beliefs, and fake symptoms. Normal subjects rarely endorsed any of the items. The responses of genuinely ill schizophrenic inpatients were compared with those of normal subjects who had been asked to fake malingering after being educated about the symptoms of schizophrenia and forewarned about the purpose of the test. The test significantly discriminated between genuinely ill patients and malingerers. The test correctly identified 87.3% of the schizophrenic subjects and 78.2% of the malingering normal subjects.