If soul and body are considered as two entities of different nature, the problem of their union arises. Aristotle attempts to solve this problem applying his distinction between matter and form to the living body; the soul would be the form that gives rise to the substance that is the material body. Nevertheless, there is a difficulty when dealing with the human soul: it seems, by observing its operations, that the human soul has some independence from matter. This would bring Aristotle closer to a the dualist (platonist) position that he was trying to refute. In this paper we propose that, even though Aristotle is not able to solve the problem of the soul-body union in the case of human beings, his philosophy takes charge of the observable data without reducing them to his theory, and that constitutes progress in understanding the problem.Si se consideran el alma y el cuerpo como dos entidades de naturaleza diversa, surge el problema de cómo pueden estar unidas. Aristóteles intenta resolver este problema aplicando su distinción entre materia y forma al cuerpo vivo; el alma sería la forma que da el ser a la sustancia que es el cuerpo material. Sin embargo, para el caso del alma humana surge una dificultad: pareciera que, por sus operaciones, el alma humana tiene cierta independencia de la materia. Esto acercaría a Aristóteles a la posición dualista (platónica) que intentaba refutar. En este trabajo proponemos que, aunque Aristóteles no logra resolver el problema de la unión alma-cuerpo para el caso del hombre, su filosofía se hace cargo de todos los datos observables sin reducirlos a su teoría, y eso constituye un avance en la comprensión del problema.