Randomization tests have been developed for several single-case experimental designs. It is argued, however, that the randomization tests developed by Levin, Marascuilo, and Hubert (1978) for the ABAB design and by Marascuilo and Busk (1988) for replicated ABAB designs across subjects are inappropriate. An alternative randomization procedure for the ABAB design is presented, and the appropriate corresponding randomization test is derived. It is shown how this alternative procedure has to be adapted to allow for statistical analyses of extended ABAB, parametric-variation, drug-evaluation, interaction, replication, and multiple-baseline designs. Finally, some limitations of the use of randomization tests for single-case designs are discussed, with particular reference to changing-criterion designs.