Aim: Acute bacterial and viral infections are usually associated with elevations of the mean platelet volume. We correlated infection with influenza changes in mean platelet volume (MPV), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR), to determine whether these might be predictors for the duration of hospitalization or mortality. Material and Method: A total of 122 influenza patients (54 males and 68 females), including 87 children and 35 adults, and 42 age-gender-matched healthy individuals (18 males and 24 females) including 25 children and 17 adults were included in the study. Hematologic tests were conducted on the patients and controls. Linear regression analysis was used to determine independent predictors of hospitalization. Results: The MPV was significantly higher in influenza patients [10.7 (min/max 7.5-15) fL] than in the healthy control group [7.8(min/max 5.7-10.8) fL, p<0.001]. The NLR and PLR were similar in both groups. There was no correlation between MPV, NLR, or PLR and mortality. Predictors of hospitalization were determined to be neutrophil level (NL) and NLR and PLR ratios (p = 0.00, p = 0.035 and p = 0.041, respectively). Discussion: Neutrophil, MPV, NLR, and PLR were significantly higher in the influenza group. While the MPV was not determined to correlate with the length of stay and mortality in the patient group, the higher levels of NLR and PLR and increased neutrophil levels predicted the duration of hospitalization.