Background and purpose The aim of this study was to assess the prevalence of cancer and its characteristics in patients with ischemic stroke and to compare this with cancer prevalence in the general population. Methods This was a multicenter cohort study with 2736 patients presenting with ischemic stroke or transient ischemic attack. The prevalence of cancer was assessed by interview and verified by reviewing all medical records. In stroke patients with a history of cancer, we studied the subtype of cancer and its treatment characteristics. We used the national database of The Netherlands Cancer Registry to calculate population‐based age and sex cancer standardized prevalence ratios (SPRs) for patients with ischemic stroke. Results Cancer prevalence in ischemic stroke patients was 12%, corresponding to an SPR of 1.2 [95% confidence interval (CI), 1.0–1.3]. Increased SPRs were observed for cancer of the central nervous system (SPR, 18.2; 95% CI, 9.0–27.4), head and neck (SPR, 3.4; 95% CI, 2.3–4.6), lower respiratory tract (SPR, 2.4; 95% CI, 1.5–3.3) and urinary tract (SPR, 2.1; 95% CI, 1.4–2.9), but not for other cancer types. Cardiovascular risk factors, stroke etiology, treatment and outcome were not different between patients with or without a history of cancer. Conclusions In stroke patients, the prevalence of cancer, most prominently cancer of the central nervous system, head and neck, lower respiratory and urinary tract, was higher than in the general population. Medical treatment for the prevention of stroke in cancer survivors deserves further study.