The effect of the spin–orbit interaction on non-dipole processes in atomic photoionization from s-shells is examined. New formulae are derived for the parameters γ and δ that describe the forward–backward asymmetry of the photoelectron angular distribution. It is found that δ may be non-zero, unlike in the non-relativistic central-field model. The reactions ns → εℓ and ns² → nsεℓ are considered separately and it is shown that the latter case may be economically given in terms of singlet and triplet continuum state amplitudes. The spin–orbit interaction in intermediate autoionizing states introduces a strong energy dependence into the non-dipole parameters and this may be used to determine relative phases of the continua. It is suggested that Xe 4d⁻¹nℓ odd and even parity autoionizing levels are a possible system for experimental investigation.