Introduction: Anaemia is common in children and may influence clinical outcomes during acute infections. Influenza can result in variable disease severity; however, the impact of anaemia and its severity on the duration of hospital stay among children with influenza who are treated with oseltamivir is not well established. Objectives: This study aimed to assess the association between anaemia and hospital stay in children with Influenza A and B treated with oseltamivir, and to determine whether this association differs according to age, gender and influenza type. Method: A cross-sectional study was conducted among children with laboratory-confirmed influenza. Demographic data, haemoglobin levels at admission, influenza type, and duration of hospital stay were recorded and analysed. Anaemia was defined using standard age-specific haemoglobin cut-offs. Results: The study included 82 children (48 males, 34 females) with a mean age of 48.7 months (range 3 months–13 years) and a mean hospital stay of 2.40 days (SD 1.06); 22% were anaemic. Influenza A was diagnosed in 71 children and Influenza B in 11. Overall, hospital stay did not differ significantly between anaemic and non-anaemic children, between influenza types, or between anaemic males and females (all p > 0.05). Anaemia severity was not correlated with hospital stay in the full cohort. However, in children aged ≤24 months, higher anaemia severity was moderately associated with longer hospitalisation (rho = 0.44, p = 0.035). Conclusion: According to this study , anaemia was not associated with prolonged hospital stay in children with Influenza treated with oseltamivir, and this relationship did not vary by gender or influenza type. However, greater anaemia severity was associated with longer hospital stay among children aged ≤24 months, suggesting that the clinical impact in younger children.