Metastases to the spleen are rare but have been reported for different tumor entities, including breast cancer, lung cancer, colorectal cancer, ovarian cancer, and melanoma. As an isolated event, splenic metastasis from non-small-cell lung cancer (NSCLC) is exceedingly rare. Until now, only 28 cases have been reported in the medical literature. We report the case of a 66-year-old woman with NSCLC (adenocarcinoma) who presented with a synchronous, isolated splenic metastasis. Operative removal of both primary tumor and metastasis was not possible due to multiple comorbidities. Therefore, treatment was limited to combined systemic chemotherapy and simultaneous radiation of the primary tumor, which led to partial remission of the disease. Isolated metastasis to the spleen in NSCLC has been reported only 28 times in the medical literature, most often in male patients with right-sided lung tumors, most of which were adenocarcinomas. The majority of patients were asymptomatic with respect to splenic metastasis. About half of the reported cases were isolated metachronous splenic metastases. Splenectomy seems to confer a survival advantage. We review the pertinent medical literature.