The objective of this paper is to furnish the research and design communities with a simple and convenient means of predicting quantities of engineering interest for slip flow in doubly connected microchannels. Slip flow in doubly connected microchannels has been examined and a simple model is proposed to predict the friction factor and Reynolds number product. As doubly connected regions are inherently more difficult to solve than simply connected regions, and for slip flow no solutions or graphical and tabulated data exist for nearly all doubly connected geometries, the developed simple model fills this void and can be used to predict friction factor and Reynolds number product, mass flow rate, pressure distribution, and pressure drop of slip flow in doubly connected microchannels for the practical engineering design of doubly connected microchannels. The proposed models are preferable since the effects of various independent parameters are demonstrated and the difficulty and investment is completely negligible compared with the cost of alternative numerical methods. ► This paper provides a simple means of predicting quantities of engineering interest. ► The proposed models fill this void for slip flow in doubly connected microchannels. ► This paper demonstrates the effects of various independent parameters. ► The models are a weak function of the doubly connected duct shape. ► The models indicate trends expected from future numerical data and experiments.