A study was made of 19 adults with situs anomalies (situs inversus [n = 10], situs ambiguous with polysplenia [n = 8], situs ambiguous with asplenia [n = 1]). No patient had congenital heart disease, bowel obstruction related to malrotation, or immune deficiency disorders. All 10 patients with situs inversus had mirror-image location of the abdominal organs relative to situs solitus; nine had dextrocardia, and one had levocardia. The eight adults with situs ambiguous with polysplenia demonstrated a spectrum of abnormalities. All had some degree of abdominal heterotaxy, including midline livers and gallbladders (n = 5), right-sided stomachs and spleens (n = 3), and rotational abnormalities of the small bowel and colon (n = 7). Other findings included multiple spleens (n = 7), interruption of the inferior vena cava (IVC) with azygous or hemiazygous continuation (n = 7), truncation of the pancreas (n = 6), and ipsilateral location of the aorta and IVC (n = 1). In the one patient with asplenia, a midline liver, right-sided stomach, bowel rotation abnormality, IVC interruption, and pancreatic truncation were noted. Recognition of the spectrum of situs anomalies is important because the altered anatomy associated with these anomalies may result in confusing imaging findings when seen in conjunction with acquired diseases. Copyright RSNA, 2002