Accurate diagnosis of small‐cell carcinoma of the lung (SCLC) is clinically important because of the therapeutic implications. SCLC must be distinguished from non‐small‐cell carcinoma (NSCLC) and lymphoma. Paranuclear blue inclusions (PBIs) were recently described as a feature of metastatic SCLC on air‐dried Wright‐stained bone marrow aspirate smears. To determine the utility of PBIs in distinguishing SCLC from NSCLC and lymphoma, we evaluated air‐dried Diff‐Quik‐stained smears from 103 fine‐needle aspiration (FNA) specimens and 14 touch imprint specimens. PBIs were identified in 24 (89%) of 27 cases of SCLC, in 6 (9%) of 64 non‐small‐cell carcinomas (P < 0.00001), and in two (8%) of the 26 lymphoma cases (P < 0.00001). No PBIs were seen on any of the alcohol‐fixed Papanicolaou or hematoxylin‐eosin (HandE) stained smears examined. In conclusion, PBIs appear to be a feature of SCLC on air‐dried cytologic material stained with Romanowsky type stains. In the presence of cytologic features of SCLC, the identification of PBIs provides a useful diagnostic feature for diferentiating between SCLC and NSCLC carcinomas, and between SCLC and lymphomas in FNA specimens and touch imprints from surgical specimens.