Climate is the primary determinant of agricultural productivity. In many parts of the world, including the United States, one can trace much of the year-to-year variations in climate to the El Nino-Southern Oscillation phenomenon. In 1997-98 the world experienced a severe El event and this is being flowed by a strong 1998-99 La Nina. The work underlying this develops estimates of the economic consequences of these events on U.S. agriculture. Both phases result in economic damages -- a $1.5 to $1.7 billion loss for the El Nino and a $2.2 to $6.5 billion for La Nina. The major conclusion is that ENSO events do impose costs on agriculture and consumers.