Hepatitis A was confirmed in persons who ate at a downtown Los Angeles, California, Mexican restaurant on September 14 or 15, 2005. A case-control study was not conducted because the link between the restaurant and cases was not identified until November. Many cases of hepatitis A had been reported in Los Angeles in October. The link between the illnesses and the restaurant was not made until there was opportunity to completely interview the cases. The restaurant was inspected in November. No food handling violations were found. There was no evidence that there had been ill food handlers, although no laboratory testing of food handlers was conducted. The restaurant did not use the same produce suppliers that were linked to other concurrent outbreaks. Lettuce had been implicated in another outbreak. The hepatitis A strain was unique and new to the USA.