An analysis is presented for adsorption from a fluid in Poiseville flow to a very thin coating on the walls of a cylindrical channel. Axial diffusion is ignored, an infinite rate of the adsorption reaction is assumed, and the partition ratio is assumed to be very large. Several nonlinear Langmuir adsorption isotherms are considered. An analytical solution is obtained for an irreversible isotherm, while finite-difference solutions are presented for other isotherms. For the case of a fully developed constant-pattern concentration profile, the breakthrough curves presented are in reasonable agreement with those obtained by assuming slug flow and a constant mass transfer coefficient. The constant mass transfer coefficient for best agreement varies from that obtained with Sherwood numbers of 3.66 to 4.36, depending on the shape of the isotherm.