The electron spin effects on the surface of a nanotube have been considered throughthe spin–orbit interaction (SOI), arising from the electron confinement on thesurface of the nanotube. This is of the same nature as the Rashba–Bychkov SOIat a semiconductor heterojunction. We estimate the effect of disorder within apotential barrier on the transmission probability. Using a continuum model, weobtain analytic expressions for the spin-split energy bands for electrons on thesurface of nanotubes in the presence of SOI. First we calculate analytically theamplitudes of scattering from a potential barrier located around the axis of thenanotube into spin-dependent states. The effect of disorder on the scatteringprocess is included phenomenologically and induces a reduction in the transitionprobability. We analyze the relative role of SOI and disorder in the transmissionprobability which depends on the angular and linear momentum of the incomingparticle, and its spin orientation. Finally we demonstrate that in the presenceof disorder, perfect transmission may not be achieved for finite barrier heights.