The absence of nurses at their work is an impacting problem that confronts many health units, such a problem impedes bringing to attention with clarity and efficiency in a family medical unit, the fundamental purpose for inquiring this theme, exploring the factors that influence absence, showing four explicative models that allow us to understand this phenomenon in their context, in such a manner that the administrator of the nurse’s department has their basis. To dimension the situation, the predominate circumstances of the theme in study are explored through the analysis of the staff showing the level of absence that prevails in the unit, in relation with the obtained data, this reflects as the principal cause of unpredictable absence, the adverse labor environment, relating itself with family problems and illness. Marking clear the importance of the analysis is evident, periodic and systematic of the behavior of the absence to have opportunistic information that favorite’s the instrumentation of methods oriented to control the different associated variables favoring the efficiency of administration.