The achievable-rate region of sequential decoding for the class of pairwise reversible multiaccess channels is determined. This result is obtained by finding tight lower bounds to the average list size for the same class of channels. The average list size is defined as the expected number of incorrect messages that appear, to a maximum-likelihood decoder, to be at least as likely as the correct message. The average list size bounds developed here may be of independent interest, with possible applications to list-decoding schemes. © 1990 IEEE