This paper provides an analysis on cooling tower fouling data taken in seven 15.54 mm I.D. helically ribbed, copper tubes at R-e = 16,000. The geometric parameters include number of rib starts, helix angle, and height. A series of semi-theoretical fouling correlations as a function of the product of area indexes and efficiency indexes are developed. The mass transfer coefficient is calculated by the Von-Karman analogy. The wall shear stress is obtained from the pressure drop. The correlations and the analyses can be used directly to assess the fouling potential of helical-rib in actual cooling water systems. (C) 2010 Elsevier Ltd. All rights reserved.