Appendicitis in children younger than 3 years of age has always been of concern due to its low incidence and high perforation rate. In this study, we analyzed our experience and evaluated the factors contributing to the delay in diagnosis. During the last 18 years, there were nine children younger than 3 years of age who presented with appendicitis. Four of these patients visited our emergency department within 48 hours after the onset of symptoms, while the symptoms had already persisted for more than 48 hours in the remaining five patients before their arrival in our emergency department. Perforated appendicitis was found in all children. Once the perforation had occurred for more than 2 days, complaints of fever, abdominal distention, and diarrhea were common. Compared to patients with symptoms for less than 2 days, those with symptoms for more than 2 days were younger and had higher serum C-reactive protein levels, significantly longer operation time, duration of postoperative ileus and length of hospital stay (LOS) (p = 0.026, 0.014, 0.018, and 0.014, respectively). No mortality was noted in the entire series, but seven of the nine patients had one or more complications, which may have prolonged LOS; anemia and wound infections were the two most common problems. Since delayed diagnosis is common, a thorough understanding of the clinical course of perforated appendicitis is important. Fever, diarrhea, and abdominal distention seem to be late manifestations. Prolonged LOS, operation time, and postoperative complications may be reduced if the operation is performed earlier.