Background: Septic shock is a subtype of sepsis that is clinically identified by a requirement for the administration of vasopressors to increase the mean arterial blood pressure to 65 mmHg or greater despite sufficient fluid resuscitation, or by an increase in serum lactic acid levels by 2 mmol/L or greater. This study aimed to evaluate the effect of the cardiac pacemaker current inhibitor ivabradine on heart rate and outcome in patients with septic shock. Methods: A prospective, single blinded randomized controlled clinical trial study conducted on 102 septic shock patients. Results: regarding regression analysis indicated that Age, APACHE II, Sofa at (4th, 7th day), MAP at 4th day, NE at (4th, 7th day), HR at 4th day and ICU stay was the most factor affected mortality rate in patients with septic shock (P