Introduction: Median sternotomy is a standard method of access to the heart and large blood vessels, and is associated with severe pain and discomfort in early postoperative treatment. Poor pain control after surgery can lead to complications and prolonged recovery, and the transition of acute pain to chronic pain. The perception of pain is individual, so the therapy is adjusted accordingly. In addition to the classic approach to the treatment of postoperative pain by parenteral administration of analgesics, there is more and more evidence of the benefits of a multimodal and multidisciplinary approach to pain treatment that combines parenteral therapy with local or regional analgesia. Objective: The aim of this paper is to investigate and compare the effect of modified pectoral block on postoperative pain after median sternotomy in comparison with conventional parenteral analgesic therapy. Methods: The research was conducted among 60 patients of the Clinical Hospital Dubrava scheduled for open heart surgery via median sternotomy. Data were collected using a form created for the purposes of this research. Patients were randomly assigned to two groups of 30 in each group. Group 1 patients did not receive a Pecs II block, while group 2 patients received a bilateral Pecs II block postoperatively. Patients were extubated after meeting the extubation criteria. The duration of the ventilator was recorded. Patients were examined for pain using a visual analog scale (VAS) by evaluating at rest and coughing. Inspiratory flow rate was assessed by incentive spirometry. Results: There was no statistically significant difference between the groups in the distribution of gender (P=1.0), age (P=0.38), type of surgery (P=0.86) and Charlson Comorbidity Index (CCI, P=0.92) values. In the entire cohort, there was a statistically significant decrease in the value of the VAS score during exercises with the physiotherapist on the second postoperative day (1.68 ± 1.32 ) compared to the first postoperative day (2.32 ± 1.43 ) (P<0.001). By comparing the values of individual measurements of the VAS sum at rest, the intervention group had statistically significantly lower values of the VAS sum 18 hours after extubation (P=0.01). Conclusion: PECS2 block may help reduce pain after median sternotomy and less need for systemic analgesic.