The peripheral smear is an excellent diagnostic aid and is often a component of a complete blood count ordered downstream of a routine clinical examination. Both for the primary care physician and a highly specialized hematologist, the peripheral smear can offer valuable glimpses of disease processes and provide diagnostic clues of unusual symptoms. In this chapter, we offer 12 case examples of blood smear presentation of noncancerous and cancerous processes. We also provide a few cases where common artifacts can be seen in peripheral smears, and in one case how to technically mitigate the artifact to enable morphological assessment of cells. Other cases include certain infectious diseases, identification of parasites in circulation, abnormal lymphoid cells and common platelet, and red cell abnormalities that a practicing physician/specialist should be aware of. The illustrations provided are from classic examples and can be an easy desk reference either for the busy clinician, or for board exam preparation that can aid the graduating fellow.