The effect of axial corrugated surface roughness on fully developed laminar flow in microtubes is investigated. The radius of a microtube varies with the axial distance due to corrugated roughness. The Stokes equation is solved using a perturbation method with slip at the boundary. Analytical models are developed to predict friction factor and pressure drop in corrugated rough microtubes for continuum flow and slip flow. The developed model proposes an explanation on the observed phenomenon that some experimental pressure drop results for microchannel flow have shown a significant increase due to roughness. The developed model for slip flow illustrates the coupled effects between velocity slip and small corrugated roughness. Compressibility effect has also been examined and simple models are proposed to predict the pressure distribution and mass flow rate for slip flow in corrugated rough microtubes.