The aim of this study is to evaluate clinical benefits of recombinant adenoviral human p53 (rAd-p53) gene therapy combined with radiotherapy in prevention of oral cancer recurrence after a radical resection. A total of 51 patients with tongue cancer (TCa) and 56 patients with gingival carcinoma (GCa) satisfying the inclusion criteria were randomly assigned to two groups: the experiment group (EG) and the control group (CG). The EG group received multipoint injections of rAd-p53 into the surgical wound surface at a dose of 1 × 10¹² viral particles after a radical resection. Patients in both EG and CG were given radiotherapy at a total dose of 60 Gy at 3 weeks after surgery. All these patients were followed up for at least 3 years. Two cases (2/27) of TCa and 2 (2/30) in GCa patients had a local recurrence in EG, but 8 (8/24) TCa and 8 (8/26) GCa patients in CG had a local recurrence. Both recurrent rates of TCa (33.3%) and GCa (30.8%) in CG are statistically significantly higher than those of TCa (7.4%) and GCa (6.7%) in EG, respectively. The overall recurrent rate in EG is 7%, which is also statistically significantly lower than that (32%) in CG. The 3-year overall survival (OS) rate and 3-year disease-free survival (DFS) rate of EG is 100% and 93%, respectively. The 3-year OS and DFS rates of CG are 94 and 68%, respectively. Mild or medium fever and flu-like symptoms were more frequently observed in EG and were considered to be associated with application of rAd-p53. Post-tumorectomy wound surface injection of rAd-p53 combining with radiotherapy is a safe and effective regimen for the patients with TGa or GCa.