Experiments concerning the drag force on circular cylinders placed in an open channel with a smooth boundary are reported. The studies were carried out under subcritical flow conditions using 31 mm diameter cylinders placed at various blockage ratios. A theoretical analysis has been carried out to obtain a relationship between the three interrelated quantities - energy loss, afflux and drag force. The experimental data on drag collected during this study as well as those collected earlier have been analysed to obtain an empirical relationship for the drag coefficient of circular cylinders placed in an open channel.