Abstract: AIM:To study the segmental early relaxation phenomenon (SERP) by tissue Doppler imaging (TDI). METHODS: TDI was performed in 103 patients with coronary heart disease and 50 normal subjects. The segmental early diastolic velocity pattern was classified as SERP, postsystolic shortening (PSS) and normal pattern. Relations between the diastolic velocity pattern and coronary diameter stenosis were analyzed. RESULTS: SERP and PSS were significantly associated with actual coronary stenosis (odds ratio=4.39 and 5.59, both P<0.01). However, in each individual patient, SERP had a higher probability of appearing in the territory supplied by the artery with the relatively mildest stenosis (odds ratio=12.53, P<0.01), whereas PSS had a lower probability in the territory with the relatively mildest and secondary coronary stenoses (odds ratio=0.33 and 0.41, P<0.01). CONCLUSION: The segmental early diastolic peak velocity may appear in the isovolumic relaxation period and not necessarily only during the rapid filling phase. This phenomenon occurs more frequently in the perfusion territory of the artery with relatively mild stenosis, which may play a role in compensation for the delayed relaxation of PSS segments to maintain isovolumic status of the left ventricle.