Aim/objectives: This study aimed to systematically review the literature on the impact of delay in diagnosis and treatment of oral cavity cancer. Methods: PubMed and Embase were systematically searched for articles reporting impact of delay in diagnosis and treatment on cancer-stage and survival of oral cavity cancer. Studies comprising at least ten patients, and published since the year 2000, were included. Results: Sixteen studies (n = 45,001, range: 62–18,677 per study, 83% men), from Australia, Asia, Europe, North America and South America, met the inclusion criteria. Eleven studies (n = 1,460) examined delay in diagnosis, while five studies (n = 43,541) reported delay in treatment. Eight of the eleven studies, examining delay in diagnosis (n = 1,220), analyzed the correlation between delay in diagnosis and tumor stage at diagnosis. Three studies found a significant correlation between patient delay and advanced stage at diagnosis (p < 0.05), whereas three other studies did not. The studies reporting a significant correlation were from Asian countries, whereas the three studies that did not find a correlation were from other continents. Studies reporting on professional delay and total diagnostic delay, generally, did not find a significant correlation with advanced cancer at diagnosis. Time to treatment (TTI), defined as time from diagnosis to treatment, was found significantly correlated with survival in three studies (p < 0.01, p < 0.001, p < 0.05), and nonsignificant in two studies. Conclusion: A significant correlation between patient delay and advanced stage cancer was reported in Asian studies only, while professional delay and total diagnostic delay were generally found to be non-correlated with advanced stage cancer at diagnosis. TTI was in some studies reported to be correlated with poorer outcome, while other studies did not report a correlation. One study presented that there was no clear advantage in overall survival (OS) for patients treated within 30 days, compared to patients treated between 30 and 44 days.