Background: Screening glioma patients regularly for possible mood disorders may facilitate early identification and referral of patients at risk. This study evaluated if the EORTC QLQ-C30 Emotional Functioning (EF) scale could be used as an initial screening measure to identify patients possibly having a mood disorder. Methods: EORTC QLQ-C30 EF and Hospital Anxiety and Depression Scale (HADS) scores were collected as part of a study assessing the impact of timing of patient-reported outcome assessments on actual health-related quality of life outcomes (N = 99). Spearman correlations and Mann-Whitney U tests were used to determine the association between the EF and HADS (sub)scales. Receiver Operating Characteristic analyses were performed to determine optimal cut-off EF scores to identify patients possibly having a mood disorder (i.e. HADS subscale score ≥8 points). Results: EF and HADS (sub)scales correlated moderately (HADS-A: r = −0.65; HADS-D: r = −0.52). Significant EF score differences were found between patients with HADS ≥8 versus <8 points (HADS-A: mean difference (MD) = 32 and HADS-D: MD = 23). The EF scale had excellent (HADS-A; AUC = 0.88) and borderline excellent (HADS-D; AUC = 0.78) distinguishing capabilities. A statistically optimal (EF score <80) and a most inclusive (sensitivity of 100%, corresponding to an EF score <97) EF cut-off score correctly identified 88.0% and 96.0% of patients with a possible mood disorder, respectively. Conclusion: EORTC QLQ-C30 EF scale seems to be an appropriate screening measure to identify glioma patients possibly having a mood disorder in need of further assessment.