Background: The objective of our study was to evaluate the prevalence of DNA of HSV I, II, CMV, EBV, HPV6.11, HPV16, HPV18 in normal oral mucosa and oral squamous cell carcinoma (OSCC), and determine this association with long-term treatment outcomes and patient survival. Methods: The study included 116 patients with OSCC (stage I-IVB who received standard treatment) and 50 healthy volunteers, median age 60.0 yrs (95% CI 58.0-64.0). Using real-time PCR (polymerase chain reaction), freshlyfrozen samples of the tumor and normal mucous membranes of the cavity were analyzed. mouths, which, after collection, were placed in an EDTA solution and frozen at 20°C. Results: In 54 (46.55%) OSCC and 17 (34.00%) normal mucous viral DNA was not found (p = 0.13). The occurrence of DNA (OSCC vs. normal) of the following viruses was the same in both OSCC and normal mucosa: HSV I, II: 2 (1.72%) vs. 2 (4.00%) (p = 0.38); EBV: 40 (34.48%) vs. 15 (30.00%) (p = 0.57); CMV: 5 (4.31%) vs. 2 (4.00%) (p = 0.93); HPV6.11: 16 (13.79%) vs. 6 (15.00%) (p = 0.84); HPV16: 12 (10.34%) vs. 2 (4.00%) (p = 0.18). HPV18 DNA: 20 (17.24%) vs. 24 (48.0%) (p <0.0001) was found significantly less frequently in the OSCC group. In addition, EBV + HPV18: 7 (14.00%) vs. 5 (4.31%) (p = 0.0270) was more common vs. OSCC in the group of healthy volunteers; CMV + HPV18: 2 (4.00%) vs. 0 (p = 0.0302). In the OSCC group, patients with stage III disease were more often virus-positive (p = 0.0137); the pterygo-maxillary fold region (p = 0.0438); with partial keratinization of cells (p = 0.05). PFS in the HPV18 (+) OSCC group was 38.5 months (95% CI 11.00-66.0) and 23.5 m higher than the group of HPV18 (-) patients (HR = 0.63; 95% CI 0.39-1.03; p = 0.0399). In virus-negative patients, PD was more often recorded: 12 (24.00%) vs. 2 (3.03%) (p = 0.0006). In the group of virus-positive patients, OS and PFS, even with non-radical treatment, were significantly higher than virus-negative patients with radical treatment. OS: vir (+)/non-radical = 69.0 mo vs. vir (-)/radical = 15.0 mo (HR = 0.22; 95% CI 0.11-0.47; p <0.0001). PFS: vir (+)/non-radical = 56.0 mo vs. vir (-)/radical = 11.0 mo (HR = 0.20; 95% CI 0.09-0.45; p <0.0001). Conclusions: The association of OSCC with viral DNA, especially HPV18, is a favorable prognosis of the disease and a longer OS and PFS, even when radical treatment is not possible.