Computed tomography (CT) guided fine needle aspiration biopsy (CT-guided FNAB) represents the procedure of choice for diagnosing peripheral primary lung cancer before surgery. The aim of the present study was to assess the reliability of the immunocytochemical evaluation of biological parameters and DNA flow cytometry on cellular material obtained from non-small cell lung cancer (NSCLC) patients by CT-guided FNAB. Thirty consecutive CT-guided FNABs obtained from NSCLC patients were submitted both to the immunocytochemical evaluation of p53, Ki67, bcl-2 and to flow cytometric DNA analysis. p53, Ki67 and bcl-2 were assessable in 60% (18/30), 53% (16/30) and 48% (10/21) of the cases, respectively. Flow cytometric DNA analysis was performed in 19 out of the 30 cases and 74% (14/19) of the histograms were evaluable. Cytofluorimetric S-phase fraction (SPF), was obtained in 57% (8/14) of the cases. The results of the current study suggest that CT-guided FNAB from primary NSCLC patients may represent an effective practice for the evaluation of biologic parameters and could be useful as a preoperative procedure. The role of neoadjuvant chemotherapy in operable NSCLC is still under debate. We suppose that in the future the presurgical characterization of NSCLC could suggest the opportunity of a neoadjuvant systemic treatment aimed to improve the clinical outcome. Moreover, in locally advanced or metastatic NSCLC immunocytochemistry could help to predict the response to chemotherapy and/or radiotherapy, avoiding ineffective treatments and supporting the development of more rational therapies.