Background and Purpose— Several constitutional and environmental risk factors may be involved in the occurrence of spontaneous cervical artery dissection (SCAD). This work explored the association between recent infection and SCAD in an hospital-based case-control study. Methods— Forty-seven patients with SCAD and 52 with ischemic stroke from another cause were prospectively and consecutively recruited by 2 neurology departments. A specially designed questionnaire was used to assess the history of an acute infection that could have occurred within a month before the vascular event. Results— Acute infection was more frequent in patients with SCAD (31.9%) than in control subjects (13.5%) (crude odds ratio, 3.0; 95% confidence interval, 1.1 to 8.2; P =0.032). This association was stronger in patients with multiple (odds ratio, 6.4) than single artery (odds ratio, 2.1) dissection. Conclusions— Recent infection is a risk factor and could be a trigger for SCAD.