Sonographic identification of thickening of the gallbladder wall that consists of multiple striations (alternate hypoechoic and hyperechoic layers) has been considered strong evidence of the presence of acute cholecystitis. We studied 27 patients in whom sonograms showed striated thickening of the gallbladder wall to determine the diagnostic significance of this finding. Striations were classified as focal or diffuse. Sonograms were correlated with pathologic findings in 16 patients and with clinical diagnoses and laboratory findings in 11. Patients were categorized as having cholecystitis with or without gangrene or edema of the gallbladder wall unrelated to gallbladder disease. Striated thickening of the gallbladder wall was due to cholecystitis in 10 patients, and all 10 had gangrenous changes at surgery or at pathologic examination. Striations were focal in eight of these patients and diffuse in two. Striated thickening of the gallbladder wall was due to edema of the wall unrelated to gallbladder disease in 17 patients. Causes included congestive heart failure (n = 4), renal failure (n = 5), liver disease (hepatic failure [n = 1], hepatitis [n = 6]), ascites (n = 2), hypoalbuminemia (n = 3), pancreatitis (n = 1), blockage of the lymphatic/venous drainage of the gallbladder (n = 2), and prominent Rokitansky-Aschoff sinuses (n = 1). More than one abnormality was present in five patients. Striations were focal in 11 of these patients and diffuse in six. The sonographic finding of striated gallbladder wall thickening is no more specific for cholecystitis than the observation of gallbladder wall thickening by itself, and it may occur in a variety of diseases. However, in the clinical setting of acute cholecystitis, the presence of striations suggests gangrenous changes in the gallbladder. The extent of the striations (focal or diffuse) is not useful in predicting the cause of the striated gallbladder wall thickening.