Diagnostic delay in oropharyngeal cancer may be associated with poor prognosis. As controversy exists on this topic because of contradictory results, the aim of this study was to perform a systematic review of the relationship between total diagnostic delay and advanced disease stages. A systematic search of MEDLINE, EMBASE, and ISI proceedings was made to identify observational studies that provided relative risks (RRs) and 95% confidence intervals (CIs) for patients with confirmed pathological diagnosis. The outcome of interest was disease stage (TNM classification), while the exposure of interest was the total diagnostic delay. The study-specific adjusted log RRs for cohort studies were weighted by the inverse of their variance to compute a pooled RR and its 95% CI. The fixed-effects pooled RR of advanced stages of oropharyngeal cancer when diagnostic delay is present was 1.32 (95% CI: 1.07-1.62). This association was stronger when the analysis was restricted to oral cancer (pooled RR: 1.47; 95% CI: 1.09-1.99) and when delay was longer than 1 month (pooled RR: 1.69; 95% CI: 1.26-2.77). The probability for patients with delayed diagnosis to present an advanced-stage tumour at diagnosis was significantly higher than that of patients with no delay in diagnosis. However, new prospective studies with strict methodology are needed to shed more light on this association.