Heart and brain fatty acid binding proteins (H-FABP, B-FABP) are markers for stroke. The invention provides a diagnostic assay for either of these markers, preferably by ELISA using a anti-H-FABP or B-FABP antibody. Since H-FABP is also a marker for acute myocardial infarction (AMI), to distinguish stroke from AMI requires an assay specific to AMI, e.g. using troponin-1 or CK-MB as a marker, also to be carried out.