This book is a text aimed primarily at Undergraduate Medicine students, due to the need to have a bibliography of basic exam topics as well as other chapters that should be reviewed in later years, but always prioritizing humans, as healthy beings. or as patients with a pathology, whether acute or chronic, with or without an etiological diagnosis. It should be noted that terms with integrative concepts have been used, discarding some classic and common ones that do not agree with the conception. Consequently, not everything written will have to be reviewed and assimilated by V and VI cycle students, but rather they will study a smaller syllabus and making very evident the interrelation in the semiological exploration, the interrogation with risk factors and the incubation period. Likewise, the physiological reference values of normality in healthy people in the population are defined; since in devices and manuals there are very extensive figures without defining the age groups, sex, physiological state, and compensatory situations that when giving a reference value sometimes reach decompensation and is interpreted as an excuse without quality control. The concepts of Clinical Pathology and Laboratory Medicine are defined, which leads us to have clarity in the chapters of the text.