Background: The purpose of this study was to assess the diagnostic role of preoperative hematological parameters, especially neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and mean platelet volume (MPV) in germ cell testicular malignancies and their prediagnostic role in staging of testicular cancer. Materials and Methods: In this cross-sectional retrospective study, we analyzed 39 patients who underwent radical orchiectomy due to a testicular cancer (Group 1) and 82 patients on whom varicocelectomy procedure was performed as control group (Group 2) between January 2006 and January 2016 in our clinic. Evaluation of the preoperative hematological parameters in both groups and also the subgroups in malignancy group according to histopathological stages was conducted in this study. Results: When the hematological parameters were compared, a statistically significant difference was found between the two groups in terms of neutrophil counts, NLR, PLR, and MPV. NLR and PLR were significantly higher and MPV was significantly lower in testicular cancer group compared to the control group. NLR was 3.1 +/- 1.4 and 2.0 +/- 1.5, PLR was 141.3 +/- 53.2 and 115.7 +/- 44.8, and MPV was 8.9 +/- 1.0 and 9.3 +/- 1.1 for testicular cancer and control groups, respectively (P < 0.05). Furthermore, differences were observed between only mean corpuscular volume, mean corpuscular hemoglobin, and MPV (P < 0.05) in different stages of malignancy. Conclusion: In accordance with these findings, NLR, PLR, and MPV may be helpful for prediagnosis of testicular malignancies. Hematological parameters will become important in the preoperative assessment for those patients.