Objective: Identify the frequency of negative appendectomy (NA) and associated factors associated in a private hospital in Lima. Methods: Retrospective study of all appendectomies performed between 2012 and 2013 at a private hospital of Lima-Peru. We reviewed the medical records of patients who underwent appendectomy and had a medical report of emergency. We excluded the ones without pathology reports. Adjusted ORs were calculated with a logistic regression model to identify factors associated with AN. Results: Three hundred seventy-six appendectomies were performed for suspected appendicitis 55.9% in women). The average patient age was 33.4 ± 17.6 years. We identified 28 AN cases of 363 patients (7.7%). We found that pain in right flank (aOR: 5.4; 95%CI: 1.4-20.8), negative Mc Burney (aOR: 3.6; 95%CI: 1.3-10.5), pain in hypogastrium (aOR: 3.1; 95%CI: 1.1-8.4) and no leucocitosis (aOR: 2.9; 95%CI: 1.2-6.7) were associated factors to AN. Gynecologic conditions (53.6%) and complicated diverticular disease (14.3%) are the most common diagnosis in AN cases. Conclusion: The obtained results indicate that the presence of pain in the right flank, negative Mc Burney, pain in hypogastrium and no leukocytosis are factors that can be taken into account to prevent negative appendectomy.