BACKGROUND Neoplastic pericardial effusion(NPE) is a rare consequence of rectal cancer and carries a poor prognosis. Optimal management has yet to be determined. Fruquintinib is an oral anti-vascular endothelial growth factor receptor tyrosine kinase inhibitor approved by the China Food and Drug Administration in September 2018 as third-line treatment of metastatic colorectal cancer.CASE SUMMARY Herein, we report an elderly patient with NPE from rectal cancer who responded to the use of fruquintinib. In March 2015, a 65-year-old Chinese woman diagnosed with KRAS-mutated adenocarcinoma of the rectum was subjected to proctectomy, adjuvant concurrent chemoradiotherapy, and adjuvant chemotherapy. By October 2018, a mediastinal mass was detected via computed tomography. The growth had invaded parietal pericardium and left hilum, displaying features of rectal adenocarcinoma in a bronchial biopsy. FOLFIRI and FOLFOX chemotherapeutic regimens were administered as first-and second-line treatments. After two cycles of second-line agents, a sizeable pericardial effusion resulting in tamponade was drained by pericardial puncture. Fluid cytology showed cells consistent with rectal adenocarcinoma. Single-agent fruquintinib was initiated on January 3, 2019, as a third-line therapeutic. Ten cycles were delivered before the NPE recurred and other lesions progressed. The recurrence-free interval for NPE was 9.2 mo, attesting to the efficacy of fruquintinib. Ultimately, the patient entered a palliative care unit for best supportive care.CONCLUSION Fruquintinib may confer good survival benefit in elderly patients with NPEs due to rectal cancer.