The evolving phases of acute appendicitis were studied experimentally. Sixty female rabbits (Oryctogalus cuniculus) of New Zealand lineage weighing about 2510 to 3040 g were divided in two groups: a control group and experimental group. The experimental group was divided into three subgroups for observation after 12, 24 and 48 hours of the operation, that consisted on a 4-0 polypropylene circular suture at 8 cm from the distal part of the cecal appendix. The control group was sham operated. The macroscopic exam (increase of the appendix volume, necrosis, perfuration, adherence and secretion in the abdominal cavity) and the microscopic finding showed a progression in the anatomopathological alterations. There was a close relationship between the histopathological findings and time after the appendiceal obstruction. We conclude that the method causes acute appendicitis and that the anathomo pathological alterations depends on the time elapsed between the operation and the postoperation findings.