This paper presents the results of a series of experiments on forced convective condensation inside coiled, doubly-fluted tubes. Two different doubly-fluted tubes were investigated in this study, and experiments showed significantly different condensation coefficients for the two. As a basis for comparison, a computer model was also implemented based on the work of Taborek et al. to predict forced convective condensation in plain horizontal tubes with equivalent dianeters. This model makes use of flow-regime-dependent local condensation coefficients. The predicted values were compared with the experimentally measured values, and these comparisons were used to suggest a mechanism for condensation in the coiled, doubly-fluted tubes. The comparisons suggest that a different mechanism governs condensation in each tube, and this can be related to the shape of the flutes.Units: Dual