The flow around a circular cylinder with a few interference elements shifted along the wake was investigated. This paper is mainly concerned with the case where a circular cylinder of the same diameter as that of the main cylinder was used as an interference element. In fact, this situation coincides with the flow around two circular cylinders in staggered arrangement that had been studied extensively. In the present study, however, a different point of view was adopted. Attention was devoted to a critical nature of the base pressure of the upstream fixed cylinder. As the downstream cylinder was shifted upstream, the base suction exhibited a critical fall at a certain gap for different levels off the wake centerline. The spatial trace of the critical gaps was compared with those of the experiments using thin splitter plates as an interference element. © 2002 Elsevier Science Ltd. All rights reserved.