The man who received the first penis transplant in the United States left a hospital on Wednesday, three and a half weeks after the operation. He is recovering well, with good blood flow to the transplanted organ and no signs of rejection, his doctors said.

“Everything seems to be healing,” said the patient, Thomas Manning, 64, a bank courier from Halifax, Mass. “Everything’s fine. It’s going to get better, too.”

Mr. Manning needed the transplant because his penis was removed in 2012 to treat cancer. The replacement organ, from a deceased donor, was attached during a 15-hour operation on May 8 and 9 at Massachusetts General Hospital in Boston.

“He’s doing great,” said Dr. Curtis L. Cetrulo, a plastic and reconstructive surgeon. “So far, so good. We’re very pleased.”