While recent guidelines for the treatment of acute heart failure syndromes (AHFS) recommend pharmacotherapy with vasodilators in patients without excessively low blood pressure (BP), few reports have compared the relative efficiency of vasodilators on hemodynamics in AHFS patients. The present study aimed to assess the differences in hemodynamic responses between intravenous carperitide and nicorandil in patients with AHFS. Thirty-eight consecutive patients were assigned to receive 48-h continuous infusion of carperitide (n = 19; 0.0125–0.05 μg/kg/min) or nicorandil (n = 19; 0.05–0.2 mg/kg/h). Hemodynamic parameters were estimated at baseline, and 2, 24, and 48 h after drug administration using echocardiography. After 48 h of infusion, systolic BP was significantly more decreased in the carperitide group compared with that in the nicorandil group (22.1 ± 20.0 % vs 5.3 ± 10.4 %, P = 0.003). While both carperitide and nicorandil significantly improved hemodynamic parameters, improvement of estimated pulmonary capillary wedge pressure was greater in the carperitide group (38.2 ± 14.5 % vs 26.5 ± 18.3 %, P = 0.036), and improvement of estimated cardiac output was superior in the nicorandil group (52.1 ± 33.5 % vs 11.4 ± 36.9 %, P = 0.001). Urine output for 48 h was greater in the carperitide group, but not to a statistically significant degree (4203 ± 1542 vs 3627 ± 1074 ml, P = 0.189). Carperitide and nicorandil were differentially effective in improving hemodynamics in AHFS patients. This knowledge may enable physicians in emergency wards to treat and manage patients with AHFS more effectively and safely.