Electron transport in semiconducting zigzag carbon nanotubes is studied by solving the Boltzmann transport equation using the single-particle Monte Carlo technique. The electronic band structure is based on a standard nearest-neighbour tight-binding parameterization, and the phonon spectrum is calculated using a fourth nearest-neighbour force constant model. The electron-phonon scattering probabilities are calculated within a tight-binding formalism. The steady-state drift velocities for the semiconducting zigzag nanotubes (8, 0), (10, 0), (11, 0), (13, 0), and (25, 0) are computed as functions of electric field strength and temperature, and the results are analysed here. The results show the presence of negative differential resistance at high electric fields for some of the nanotubes. The drift velocity and the low-field mobility reach a maximum value of congruent to 4.67 x 10(7) cm s(-1) and congruent to 4 x 10(4) cm(2) V-1 s(-1), respectively, for a (25, 0) nanotube.