Tongue function assessment typically forms part of a clinical bedside swallowing evaluation (CBSE). The predictive value of lingual function for calculating aspiration risk in isolation is not known. The aim of this systematic review was to collate current evidence on the utility of assessing lingual deficits for predicting aspiration. Health databases Medline, CINAHL, Cochrane Library, SpeechBITE, AMED and Embase were searched from inception to November 2016. Studies were included if there was a comparison between a clinical lingual assessment (index test) and aspiration on instrumental assessments (reference test) in adults who had been diagnosed with oropharyngeal dysphagia. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used to assess the quality of the studies. Sensitivity, specificity, predictive values, likelihood ratios and odds ratios were extracted or calculated where possible. A best evidence synthesis and receiver operator curve (ROC) analysis for sensitivity and specificity were conducted. Twelve studies were included, of which only one had a low risk of bias. The ROC curve, predictive values and likelihood ratios did not show a relationship between lingual function and aspiration. Best evidence synthesis showed moderate evidence that when motility and strength are jointly assessed, they are not associated with aspiration. Other lingual assessment variables indicated either limited or conflicting evidence of an association. There is currently no evidence to indicate that there is a predictive relationship between lingual deficits as part of a CBSE and aspiration in adults with acquired oropharyngeal dysphagia. Recommendations for clinical practice and future research are made.