In 1955, the area infested by Aedes aegypti in Argentina was estimated as 1,500,000 km2; and in 1963, the species was considered to be eradicated from Argentina. In 1995, the Argentine Ministry of Health reported reinfestation by Ae. aegypti. During 1994-95, the Ministry of Health of Cordoba Province, Zoonosis Department, established a surveillance system for Ae. aegypti in Cordoba Province, Argentina. This report is a summary of results obtained thus far. In total, 74 localities in Cordoba Province were sampled during August 1994-April 1996, resulting in 5 positives (6.7%): Villa Maria city, Villa Nueva, and Cordoba city in 1995, and Juarez Celman and Jesus Maria in 1996. In Villa Maria and Villa Nueva, Ae. aegypti was present until June 1995 (autumn) and reappeared in December 1995. In Cordoba city, Ae. aegypti was eliminated from the only positive house in May 1995, but it reappeared in March 1996. Reappearance of Ae. aegypti in this temperate area in early summer may have been due to the survival of individuals during winter and not to reintroduction during summertime. The last previous active surveillance for Ae. aegypti in Cordoba Province was carried out more than 30 years ago.