This paper addresses the detection improvement of Gate Oxide Short defect using a delay test strategy. To achieve this objective, the concept of detectabil-ity interval is first introduced in the context of detec-tion of short defects using Boolean test technique. Then this paradigm is extended to the detection of Gate Oxide Short defects using delay testing. Final-ly, it is shown that it is possible to significantly im-prove the detection of this kind of defect.