Objective To determine whether CD63, p63 and CD56, are useful in the diagnostic evaluation of cytologic samples of pulmonary malignancy. Study Design We explored the utility of using a panel of 13 antibodies, CD63, p63 and CD56, for the diagnosis of lung cancer in cytologic samples consisting of 40 cases of cell block sections and previously Papanicolaou-stained cytologic smear slides. Results The positive rates for CD63, p63 and CD56 were as follows: adenocarcinoma (18/19), (0/19) (0/19) for small cell lung carCinowa (3/8), (0/8), (8/8), and for squamous cell carcinoma (0/13), (12/13), (0/13). All p63 positive cases were squamous cell carcinoma, and all CD56 positive cases were small cell lung carcinoma. CD63 was positive in the majority of adenocarcinomas. Conclusion The panel of CD63, p63 and CD56 appears to be useful in the diagnostic evaluation of cytologic samples of pulmonary malignancy. (Acta Cytol 2010;54:55-59)