Toxoplasmosis complicating lung cancer has been described only rarely. Here, we report a case of acute Toxoplasma gondii infection in a patient with squamous lung cancer. A 64-year-old woman was admitted to our hospital with a history of cough of 6 months' duration and chest pain of 1 week's duration. Further examination revealed multiple swollen lymph nodes, palpable on the top of the right collarbone and without tenderness. The chest X-ray, bronchoscopy, and computed tomography scan confirmed squamous carcinoma of the right lung. The Wright-stained bronchoalveolar-lavage fluid cytology diagnosis was positive for T. gondii and tachyzoites were detected. All of them were of free type (ectocytic), without intracellular parasites. Serological examination revealed that the anti-T. gondii immunoglobulin (Ig) M and IgG antibodies were positive. Unfortunately the patient did not continue treatment and was lost to follow-up. Toxoplasmosis is a life-threatening opportunistic infection in patients with lung cancer. Prompt recognition of T. gondii infection among cancer patients with subsequent targeted treatment of toxoplasmosis could help alleviate symptoms and improve survival.