The study of the internal state of sickness constitutes one of the mayor lines of research work with ample perspectives of developmemt for the application of psychological knowledge in regards to internal ailments. It constitutes one of the principal chapters of contemporary patopsychological research and is an expression of the increasing use of Patosychology for diagnosis and psychological correction of illness caused by different pathologies, which are frequently present in hospitals and other institutions. The need for studying the internal state of illness was set forth by A.R. Luria as for back as 1944, and has been frequently mentioned by psychologists and doctors en a world wide scale. The aim of this communications is to underline the need of development of research with cuban patients in this area of study, and to present the basic theories and studies carried out until now, together with the results of some recent research carried through by cuban psychologists. It also intends to set forth the practical and theoretical meaning of work in this line, and present actual problems in the medical and psychological sciences, wich could be considered fundamental for research work. Consequently, it proposes, lines of future scientific development, in which doctors and psychologists will be able to find clinical practical tasks and individual research, within the area of everyday assistance, and with an authentic interdisciplinary character.