It has been reported that 5.1-7.0% of acute pericarditis are carcinomatous pericarditis. Malignant pericardial effusion (MPE) can progress to cardiac tamponade, which is a life-threatening condition. The effectiveness and feasibility of intrapericardial instillation of carboplatin (CBDCA; 150 mg/body) have never been evaluated in patients with lung cancer, which is the most common cause of MPE. Therefore, we evaluated the effectiveness and feasibility of intrapericardial administration of CBDCA following catheter drainage in patients with lung cancer-associated MPE. In this retrospective study, 21 patients with symptomatic lung cancer-associated MPE, who were administered intrapericardial CBDCA (150 mg/body) at Gunma Prefectural Cancer Center between January 2005 and March 2018, were included. The patients' characteristics, response to treatment, and toxicity incidence were evaluated. Thirty days after the intrapericardial administration of CBDCA, MPE was controlled in 66.7% of the cases. The median survival period from the day of administration until death or last follow-up was 71 days (range: 10-2435 days). Grade 1-2 pain, nausea, fever, and neutropenia were noted after intrapericardial CBDCA administration. No treatment-related deaths were noted in the current study. Intrapericardial administration of CBDCA (150 mg/body) did not cause serious toxicity, and patients exhibited promising responses to lung cancer-associated MPE. Prospective studies using larger sample sizes are needed to explore the efficacy and safety of this treatment for managing lung cancer-associated MPE.