<p>Background. Synchronous multiple primary malignant tumors, including primary lung cancer, are rare entities. Among them, synchronous primary lung cancer and malignant lymphoma is extremely rare. Case. A 52-year-old man presented with a 1.8 cm lobulated solid pulmonary nodule in the right upper lobe and right inguinal and external iliac lymphadenopathy on computed tomography. Positron emission tomography-computed tomography revealed increased fluorodeoxyglucose uptake in the pulmonary nodule, right inguinal lymph nodes, and right external iliac lymph nodes, with maximum standardized uptake values of 9.4, 4.3, and 5.3, respectively. We performed lung and inguinal lymph node biopsies simultaneously under general anesthesia for diagnostic and treatment purposes. We performed diagnostic wedge resection first, and the frozen diagnosis revealed poorly differentiated carcinoma, which was indicative of primary lung cancer. Thus, we performed radical lobectomy and systematic lymph node dissection. Subsequently, we performed an inguinal lymph node biopsy. Finally, we made a pathological diagnosis of stage IB small cell lung cancer (SCLC) and stage IIA Hodgkin's lymphoma (HL). The patient underwent adjuvant chemotherapy for SCLC followed by chemoradiotherapy for HL, under consideration that the prognosis of limited-stage HL was better than that of early-stage SCLC. The patient had no tumor recurrence for 29 months after surgery. Conclusion. We reported a rare case of synchronous SCLC and limited-stage HL that was detected from a peripheral pulmonary nodule and inguinal and iliac lymph node swelling. For the diagnosis of a synchronous pulmonary nodule and inguinal and iliac lymphadenopathy, we should differentiate various entities, including lymph node metastasis from primary lung cancer and metastasis from pelvic neoplasms. Furthermore, we should provide curative treatment for both malignancies in consideration of the patient's prognosis, chemotherapy regimen, and general condition. </p>