In this paper, we propose an oscillation-based test methodology for sequential testing. This approach provides many advantages over traditional methods. (1) It is at-speed testing, which makes delay-inducing defects detectable. (2) The ATPG is much easier, and the test set is usually smaller. (3) There is no need to store output responses, which greatly reduces the communication bandwidth between the Automatic Test Equipment (ATE) and Circuit under Test (CUT). We provide a register design that supports the oscillation test, and give an effective algorithm for oscillation test generation. Experimental results on MCNC benchmarks show that the proposed test method achieves high fault coverage with smaller number of test vectors.