['To compare circulating concentrations of N terminal pro-brain natriuretic peptide (N-BNP) and cardiotrophin 1 in stable and unstable angina.', 'Observational study in a teaching hospital.', '15 patients with unstable angina, 10 patients with stable angina, and 15 controls.', 'Resting plasma N-BNP and cardiotrophin 1 concentrations.', 'N-BNP concentration (median (range)) was 714 fmol/ml (177-3217 fmol/ml) in unstable angina, 169.5 fmol/ml (105.7-399.5 fmol/ml) in stable angina (p = 0.005 v unstable angina), and 150.5 fmol/ml (104. 7-236.9 fmol/ml) in controls (p < 0.0001 v unstable angina; NS v stable angina). Cardiotrophin 1 concentration was 142.5 fmol/ml (42. 2-527.4 fmol/ml) in unstable angina, 73.2 fmol/ml (41.5-102.1 fmol/ml) in stable angina (p < 0.05 v unstable angina), and 27 fmol/ml (6.9-54.1 fmol/ml) in controls (p < 0.0005 v stable angina; p < 0.0001 v unstable angina). Log cardiotrophin 1 correlated with log N-BNP in unstable angina (r = 0.93, p < 0.0001).'] Are plasma N terminal pro-brain natriuretic peptide and cardiotrophin 1 raised in unstable angina?