The diagnosis of care problems is a complex process that involves many variables and inferences. This competence begins to acquire during the student stage, but matures later. The qualified professional continues to settle and perfect this judgment ability. Expert Systems are technologies that can help in making decisions such as diagnosis. The objective of this study is to build an Expert System in order to help in diagnosis of care problems by means of taxonomic triangulation technique. The deductive method follows three phases that result in the representation of expert knowledge through an associative network, the construction of a verified and validated prototype and, finally, the design of an app through a document of requirements specification in IEEE standard.