Tests are described on a pilot plant simulating an air-cooled heat exchanger that can be operated in both the induced-draft and forced-draft modes. Heat transfer coefficients in the induced-draft mode were well correlated, for greater than six rows, by the Briggs and Young correlation; for smaller numbers of rows, a new correlation is presented. In the forced-draft mode, however, none of the literature correlations fit the data and two new correlations (for more than six rows and for less than six rows, respectively) are presented. Data were also obtained for pressure drop and these are compared with existing correlations. Two new pressure-drop correlations are presented for the forced-draft mode.