The study was designed to investigate the association between blood pressure (BP) and urinary albumin excretion in patients with acute ischaemic stroke. A group of 54 patients were studied with first-ever ischaemic stroke, admitted within 24 hours after the onset of symptoms. Urinary albumin excretion was measured immunonephelometrically on the second day of hospitalisation in 24-hour urine collection. BP was measured on admission and then every 4 hours during 48 hours after admission. Microalbuminuria (MA) was found in 23 patients (42.5%). Microalbuminuric patients had higher BP during 48 hours after admission than patients without MA (P < 0.05, ANOVA with repeated measures). Mean daytime diastolic BP values (88.6 +/- 9 vs 82.7 +/- 9) as well as night-time systolic (148.0 +/- 18 vs 134.3 +/- 15) and diastolic BP (88.5 +/- 10 vs 80.4 +/- 7) were higher in patients with MA (p < 0.05, Student t-test). Patients with MA demonstrated no physiological decrease of night-time systolic and diastolic BP, contrary to those with normal urinary albumin excretion. Mean night-time systolic and diastolic BP correlated with urinary albumin excretion (rs = 0.37, p = 0.006 and rs = 0.39, p = 0.004, respectively, Spearman's rank correlation coefficient). On multivariate analysis the night-time diastolic BP was the most important factor influencing the occurrence of microalbuminuria (p = 0.007, logistic regression model).