Horizontal two-phase flow patterns were observed in a transparent circular channel (1.90 cm ID.) using adiabatic mixtures of air and water. Visual identification of the flow regimes was supplemented with photographic data and the results were plotted on the flow regime map which has been proposed by Breber et al. [1] for condensation applications. The results indicate general consistency between the observations and the predictions of the map, and, by providing data for different fluids and conditions from which the map was developed, support its general applicability.