A 66-year-old male was diagnosed as carcinoma larynx in the year April 2004. He was treated with concurrent chemoradiation and remained disease free for three consecutive years. After 3 years he suddenly complained of giddiness and seizures. Magnetic Resonance Imaging of brain showed features of primary CNS lymphoma (PCNSL) which was confirmed by histopathology test. To the best of our knowledge PCNSL as second malignancy in a case of carcinoma of head and neck has not been reported till date. The PCNSL in this patient may have resulted from depressed immunity due to previous radiotherapy. Whatever may be the predisposing cause, this case is most probably the first reported case of PCNSL in a patient of squamous cell carcinoma of larynx.