Esta investigación tiene como objetivo analizar y discutir, la afirmación de que las razas humanas difieren en la cantidad de masa cerebral, esto se basa en la idea racista de que los negros tienen un cerebro más pequeño que los caucásicos, para lograr el objetivo se pesa el cerebro y se correlaciona con el tamaño del cuerpo de distintas etnias.  A critical review is given of those factors which mav be accompanied by variations in brain weight, viz. sex, body sizq age of death, nuhitional state in early life, source of the sample, occupational group, cause of death, lapse of time after death, temperature after death, anatomical level of severance,Presence or absence of cerebrospinal fluid, of meninges andof blood-vessels. Valid comparisons between the brain-weightof human populations should take all, or several, of thesevariables into account; however, published studies have notdone so, despite claims to the contrarv. The ideal sample isfrom subjects who have died suddenly- without prior disease:while three such samples are on record for Europeans, nonehas been recorded for Negroes. The brain-weight of healthyNegroes is not known. Most published interracial comparisonsare invalid. The histological, chemical and functional counterparts of big and small brains in modern man are not known. Published interracial comparisons of thickness of the cerebral cortex and, particulariy, of its supragranular layer, are technically invalid: there is no acceptable proof that the cortex of Negroes is thinner in whole or in any layer, than that of Europeans. It is concluded that vast claims have been based oniusubstantial evidence.