Abstract We present results on the quantum corrections to electronic transport in narrow Si accumulation layers. These devices are four terminal structures, fabricated in a manner which allows the channel width to be varied by application of a reverse bias to p + implanted regions. At low temperatures we find one-dimensional behaviour in both the quantum interference and the electron interaction corrections to the conductivity. The temperature, T, dependence of the electron phase relaxation length L θ indicates that the dominant mechanism for phase relaxation in 1D is electron-electron scattering with small energy transfer (Nyquist noise) for which L θ varies as T −1 3 . We investigate the contribution to phase relaxation from impurity modified electron-electron (Landau-Baber) scattering, where L θ varies as T −1 4 , and the transition between this and the Nyquist mechanism. The quantum Hall characteristics are seen to depart significantly from the standard 2D behaviour, with an absence of both the odd integer plateux in ϱ xx and the associated zero resistance states in ϱ xx . For high carrier densities we observe oscillations in the transverse resistance at low fields.