We agree with Lizard's view that the most reliable method to establish the occurrence of apoptosis is microscopic morphology, because histological morphology is most distinctive of apoptosis (1, 2). However, even microscopic inspection has its limitations, in part due to the subjective nature of the assessment. As noted by Lizard, many flow cytometric assays, including those presented in our manuscript (3), cannot distinguish necrotic cells from apoptotic cells because both cell types display similar shifts in the scattergrams (2, 4). Even expression of Annexin V is not specific for apoptotic cells (5, 6). Another reason for this difficulty in distinguishing between different forms of cell death stems from the frequent occurrence of “secondary apoptosis” (1) or “apoptotic necrosis” (2) (different researchers used different names), and the absence of pure apoptosis without necrosis in a given sample (or vice versa). As documented in Figure 2 of Lizard's article (4), individual stimulants of apoptosis or necrosis induced both apoptotic and necrotic cells in vitro, at different rates. Prominent T cell death by apoptosis is a hallmark of acute infectious mononucleosis. This has been documented in earlier studies by morphological and biochemical studies (7-10). In the current study (3), we have carefully evaluated the morphology in peripheral blood smears of all the infectious mononucleosis patients, and we have confirmed that cell death during blood incubation occurred predominantly by apoptosis. As shown in Figure 1 of our article (3), the percentage of “broken cells,” a reflection of cell death by necrosis in blood smears, did not change during incubation at 37°C, whereas the number of apoptotic cells increased substantially. In the past 10 years, more than 35,000 manuscripts have been published on apoptosis. However, little information from these studies has found useful application in clinical laboratories. The main purpose of our article (3) was to bring apoptosis closer to the clinic through application of regularly used instruments, not to re-examine, by a different method, whether apoptosis occurs in the blood of patients with infectious mononucleosis. Automated hematology analyzers are used almost universally in clinical laboratories. We show that automated hematology analysis with parallel inspection of whole blood smears can be used effectively for the clinical screening of apoptotic lymphocytes in whole blood samples. Screening for apoptotic lymphocytes in the clinical laboratory is likely to provide useful diagnostic information.