Artículo de publicación ISIObjective: The objective of this study was to assess if there is increased herpes simplex virus type 1 (HSV-1) salivary shedding in oncology pediatric patients with severe cytopenia (SC). Study design: HSV-1 was detected by real time PCR in saliva samples from oncology pediatric patients (n = 30) during SC and relative cytopenia (RC), and from healthy children (n = 27). Results: The frequency of HSV-1 positive saliva samples was higher in patients with SC as compared to controls (P < .05), and this frequency presented a significant reduction during RC periods (P < .02). The SC group positive for HSV-1 presented both a twofold increase in the neutrophil-to-lymphocyte ratio as compared with SC patients negative for HSV-1 (P < .05), and a positive correlation between neutrophil and lymphocyte counts (P < .05, R = 0.82, R2 = 0.67). This correlation was not found in oncology patients negative for HSV-1 during SC and RC.