Introduction: Absenteeism in nursing is a frequent problem, of great socioeconomic impact and representing a risk for the quality of care. Objective: To describe work absenteeism and its associated factors in nurses of a third-level hospital institution. Methods: Cross-sectional and descriptive research carried out at Dos de Mayo National Hospital in Lima-Peru, during 2018. The study group consisted of 471 nurses and the random sample was made up of 72. The absence records of the years 2016 and 2017 were reviewed, and a questionnaire with prior informed consent was applied. The data were processed and analyzed using descriptive statistics. Results: 97.22% (70) belonged to the female sex, 47.22% (34) were at aged 31-44, 50% (36) were married, and 23.61% (17) were separated. The rate of absenteeism was 4%, severity was 40 hours lost per 1000 worked hours per nurses, and 6 shifts were lost per nurse yearly. Conclusions: The magnitude of total absenteeism due to nonattendances is high. Partial and unanticipated absenteeism predominated: late arrivals and leaves. The personal factors associated with absenteeism were having young children, employment relationship with another institution; having children at the same time of having elderly parents under the nurse’s care, having a chronic illness in addition to caring for their parents and having children, being a father and mother at home, besides having children, two jobs and taking care of one of their parents. The labor and extra-labor factors were difficulties in the work area, not being able to change the shift, and external training.