Introduction: CT scan-guided fine-needle aspiration (FNA) of lung nodules is a well-establisbed diagnostic technique. In our institution, both FNA and tissue core biopsy (using a 20-gauge needle) under CT scan guidance are routinely performed during the same procedure, and a preliminary diagnosis (an immediate assessment) is rendered. We compared core roll preparations (CRPs) with aspirate smears in the immediate assessment of pulmonary lesions and also assessed whether CRP resulted in the alteration of the histopathology of the core biopsy. Study design: Twenty-five cases of neoplastic pulmonary lesions diagnosed in CT scan-guided lung FNA specimens, with core biopsies performed sequentially at the same visit for each patient, were evaluated. CRPs were made by lightly rolling the tissue core on a glass slide, followed by air-drying. Only stained slides (Diff-Quik; Mercedes Medical; Sarasota, FL) were reviewed, and were scored for cellularity and morphology. Results: CRPs in seven cases (28%) scored more diagnostic points than FNA smears, and were found to be better for cellularity and morphology compared to the corresponding FNA smears. The FNA smears scored more than CRPs in 10 cases (40%), while in 8 cases (32%) both CRPs and FNA smears scored equal diagnostic points. Using both CRP and FNA smears in the immediate assessment of lung biopsy specimens, we could assign a specific malignant histologic cell type in 23 of 25 cases (92%). In comparison, if the FNA smears were evaluated alone, we could assign a specific malignant histologic cell type in only 16 of 25 cases (64%). The CRP did not alter the histopathology of the core biopsy specimens in any of the above cases. Conclusion: The CRP complements the CT scan-guided lung FNA procedure in the immediate assessment of neoplastic lung lesions without altering the histopathology of core biopsy specimens.