This paper describes the results of a retrospective study that analyzed the extent and role of diagnostic delays on the development and prognosis of oral cancer. We consulted the digital archives of the Anatomy and Pathology Department of the University Hospital of Modena and Reggio Emilia for the period from 2000 to 2016, to identify all patients with oral cavity lesions according to the SNOMED coding system. In total, 645 reports of squamous cell carcinoma of the oral cavity were retrieved. Data collected from the reports was supplemented with clinical information, with particular reference to the time of onset of the first signs and/or symptoms and the time elapsed between biopsy and definitive histological diagnosis following surgery. The average delay of patients from onset of signs and/or symptoms and seeking medical care was 112 days, or about 4 months. A longer delay was found for male with respect to female patients (151 days versus 82 days respectively; p < 0.015). An average delay of 40 days was observed between the first biopsy and the postoperative histological diagnosis. Results indicate that diagnostic delays occur frequently in oral tumours and can due to both the patient's wait-and-see conduct upon appearance of the first signs and/or symptoms, and to the organizational and communicative deficiencies among the different medical specialties. In light of these results, we make the recommendation to organize information campaigns through the Public Health Departments and specific screening programs, and to introduce an operational protocol for the prevention and early diagnosis of oral cancer, involving general medicine practitioners and dentists as the main promoters.