The use of the barium enema examination to define the presence on absence of appendiceal disease has proven to be of significant value. This evaluation in a series of patients with appendicitis and in a group of patients without appendicitis conclusively demonstrates the excellent results obtained. Findings in the barium enema study of (1) non-filling of the appendix, plus a mass, (2) non-filling of the appendix with associated findings, (3) partial filling with and without a mass, and (4) irregular filling or a "cut-off sign" are strongly suggestive, if not diagnostic, of acute appendicitis. Non-filling of the appendix occurs about 8 per cent of the time and should be considered suspicious of an appendiceal problem. Plain film roentgenographic findings, other than an appendicolith or gas within the appendix, are inconclusive and cannot indicate the nature of the problem in as specific a manner as the barium enema examination. The barium enema examination is a harmless procedure in patients with acute appendicitis and its use is urged.