Machining of thin-walled tubular geometries poses interesting problems from a process planning perspective. In machining of such geometries by milling, cutting force-induced tool and workpiece deflections have to be overcome in order to realize part accuracies without compromising productivity. This calls for a systematic study of surface errors on machined parts due to both tool and workpiece deflections. The present paper investigates the effect of cutter and workpiece flexibilities on surface error during peripheral milling of thin-walled tubular geometries. Unlike previous attempts to study milling of thin-walled straight geometries, the present work focuses mainly on machining of tubular geometries. Tubular geometries need to be treated differently from a process planning perspective by exploiting the workpiece rigidity they offer. The process planner has an option of synclastic and anticlastic machining possibilities during machining of tubular geometries which needs to be explored and understood. More importantly, the complex and varying profile of surface error with cutting conditions has to be accounted for. From the outcomes of the present work it can be summarized that surface errors in machining of closed tubular geometries are due to multiple factors which include workpiece rigidity, tool overhang, curvature effects, thinning effects, and nature of tool and workpiece engagements. All of these parameters are affected by process parameters chosen during machining. The present study also demonstrates that the understanding of surface error profiles due to cutter and workpiece deflections not only helps in realizing dimensional accuracy, but geometric tolerances as well.