A successful surgical repair of a right hepatic hydrothorax in the absence of ascites is reported. A technetium-99m scintigram that was injected intraperitoneally provided evidence of a one-way flow of fluid from the peritoneal to pleural cavity. To identify any possible minute defects in the diaphragm, carbon dioxide was insufflated into the peritoneal cavity during the operation. We performed a direct suture of the defect observed on the diaphragm. The pleural effusion subsequently vanished after the operation.