This review includes data from 23 countries. In addition there are notes concerning 6 other countries in which no positive developments during 1966 are known. Nine countries are established producers of petroleum. Collectively they contributed about 13% of the world's total oil production in 1966. Total production from these 9 countries averaged 4,247,047 b/d during 1966. This was a decrease of 41,770 b/d from the 1965 figure, the first year-to-year decline registered since 1958. Venezuela contributed 79% of the total production during 1966. There were appreciable increases, compared with 1965, from Argentina, Bolivia, Brazil, and Trinidad, totalling 64,540 b/d. This was more than offset by a decrease of 102,500 b/d in Venezuelan production. For the overall area reviewed xploration by geological and geophysical parties registered a moderate decline from the previous year. The number of exploratory wells drilled and the percentage which were successful registered small increases from last year. The activity by approximately 9 companies aimed at offshore exploration in the Central America region during 1966 continued as a significant trend in the search for oil within the area of this review. Bolivian crude oil became available to the overseas market in the last half of 1966 when a trans-Andean pipeline was placed into service.