The present study mainly concentrates on the prediction of two-phase heat transfer coefficient for saturated flow boiling conditions in minichannels. The experimental database has been generated through systematic experiments on the basis of the effect of aspect ratio. In the experiments, deionized water is used as the working fluid and five single rectangular minichannels with different aspect ratios but with the same hydraulic diameter of 1.2mm have been tested. The database (120 data points) contains mass fluxes of 70-310kg m(-2)s(-1), wall heat fluxes of 216.2-1,117.6 kWm(-2), vapor qualities of 0.012-0.788, liquid Reynolds numbers of 59.6-1,201.7, and aspect ratios of 0.25-4.00. The data obtained has been used to evaluate the previous correlations proposed for different scales (macro-mini-micro), and, then, a new empirical correlation has been developed. This new correlation presents clearly a good performance with an overall mean absolute error of 9.2%, and all the predictions fall within +/- 30% error band.