A solution is given in power series form to the problem of fully developed laminar flow in a uniformly porous tube. Although the general analysis is similar to a previous solution for a porous channel, the present tube results exhibit marked instabilities for wall suction, in contrast to the well-behaved channel results. A physical reason for the instabilities has been given in a recent paper by Weissberg, whose analysis of the inlet region indicates a breakdown in the assumption of fully developed flow.