We report a case of Klebsiella oxytoca sepsis as a complication of nonperforated appendicitis in an 11-year-old immunocompetent boy. Even if septicemia is not mentioned in major reviews as a complication of nonperforated appendicitis, several cases have occasionally been reported in adult patients in the literature. The pathogenesis of sepsis with nonperforated appendicitis is still not clear, but a mechanism of bacterial translocation has been taken into account to explain the spread of microorganisms from the intestinal lumen to the systemic blood stream. Clinicians should therefore be aware of this occurrence.