Objective To investigate the use of hematological parameters in the differential diagnosis of testis torsion and epididymo-orchitis, and to determine the predictive value of these parameters in the diagnosis of testis torsion. Methods This study retrospectively reviewed the medical data of patients who presented to our institute with the complaint of acute scrotal pain. Eighty-five patients who had undergone orchiectomy or surgical detorsion due to testis torsion and 72 patients with epididymo-orchitis were included in the study. The control group comprised 78 healthy males. The groups were compared with respect to age, hematological parameters, neutrophil to lymphocyte ratio (NLR), monocyte to eosinophil ratio (MER), and platelet to lymphocyte ratio (PLR). Results The monocyte count significantly differed between testis torsion and epididymo-orchitis, and was useful in the differential diagnosis. The mean neutrophil, platelet, and white blood cell counts, and the NLR, MER, and PLR values in the control group were significantly lower than those in the torsion and epididymo-orchitis groups. Conclusion The sensitivity and specificity of NLR in predicting testis torsion were as high as the sensitivity and specificity of doppler ultrasonography, suggesting the possible use of this parameter in the diagnosis of testis torsion.