Aims: For families under stress, positive grandparent relationships provide a valued ‘safety net’. However, grandparenting young children, and coping with unexpected family stressors can place a heavy burden on older individuals who may be experiencing declining health and energy levels. This study aimed to assess the prevalence of distress and unmet support needs in grandparents of children with cancer, compared with age, gender and rurality-matched grandparents of healthy children. Methods: Grandparents completed self-report questionnaires assessing four predictors (distress, anxiety, depression, anger) and one outcome (‘need for help’) [validated Emotion Thermometers Tool]; support service usage and barriers to access. Results: 215 grandparents participated (82 in the cancer group; 133 controls; mean age: 65.54 years (SD=6.99), 34% male). Grandparents of children with cancer reported significantly higher levels of clinically relevant distress (34.2% versus 12.8%; p<.001), anxiety (50.6% versus 23.3%; p<.001), depression (24.1% versus 5.3%; p<.001) and anger (21.8% versus 6.9%; p=0.002). They also reported a greater need for help (13.0% versus 3.1%; p=0.006). After controlling for group, gender and age, depression, anxiety and anger were significant predictors of need for help (R2=44.9%; p<.001). Grandparents of children with cancer were more likely to utilize support (70.4% versus 42%; p<.001), however formal psychosocial support was rarely accessed (<3%). Key barriers to accessing support included not knowing how to access support when needed and privacy concerns. Conclusions: Grandparents of children with cancer are more distressed, and are in greater need of help, than the norm. Their capacity to support their families may be limited by their own, untreated, distress. While anxiety is most prevalent, depression and anger are also important targets, given their relationship with need. Grandparents rarely access evidence-based psychosocial support, possibly due to lack of information and privacy concerns.