BACKGROUND: Parenting behaviours are influenced by a range of factors, including parental functioning. Although common, the influence of parental fatigue on parenting practices is not known. The first aim of this study was to investigate the relationship between fatigue and parenting practices. The second aim was to identify parental psychosocial factors significantly associated with fatigue. METHODS: A sample of 1276 Australian parents, of at least one child aged 0-5 years, completed a survey. Demographic, psychosocial (social support, coping responses) and parental sleep and self-care information was collected. Hierarchical regression was performed to assess the contribution of fatigue (modified Fatigue Assessment Scale) to parental practices (warmth, irritability and involvement), and parenting experiences (Parenting Stress Index, Parenting Sense of Competence Scale). Hierarchical multiple regression assessed the contribution of a range of parental sleep, psychosocial (social support, coping responses) and self-care variables to fatigue when demographic characteristics were held constant. RESULTS: Higher fatigue was significantly associated with lower parental competence (β=-0.17, P < 0.005), greater parenting stress (β= 0.21, P < 0.005) and more irritability in parent-child interactions (β= 0.11, P < 0.005). Several psychosocial characteristics were associated with higher parental fatigue, including inadequate social support, poorer diet, poorer sleep quality and ineffective coping styles including self-blame and behaviour disengagement. CONCLUSIONS: Fatigue is common, and results suggest that fatigue contributes to adverse parental practices and experiences. However, possible risk factors for higher fatigue were identified in this study, indicating opportunities for intervention, management and support for parents.