Aim To approach the short-term and long-term relative risks of ischemic stroke associated with clinically diagnosed transient ischemic attack(TIA),provide the reference frame for the prophylaxis and timely treatment of ischemic stroke.Methods We used a case-control study.1040 cases of ischemic stroke for the case group,and 2982 control subjects came from our hospital medical examination center.Clinically diagnosed TIA was ascertained from medical records.Logistic regression was used to calculate OR.Results In 1040 stroke cases and 2982 control subjects,Clinically diagnosed TIA was 187(17.98%) cases and 104(3.49%) respectively.Analysis focused on the most recent TIA before the index date.For TIA<1 month before the index date,the adjusted OR for stroke was 31.5(95%CI 11.6 to 88.4);For TIA 1 to 3 months before the index date,it was 19.2(95%CI 8.6 to 41.7);For TIA 4 to 6 months before the index date,it was 3.98(95%CI 1.38 to 7.93);And for TIA >5 years before the index date,it was 2.14(95%CI 1.22 to 2.85).Conclusions The relative risk of ischemic stroke was high for TIA diagnosed within the past 3 months,which was the critical period for prevention.