<sec><title>OBJECTIVE</title>To assess the predictive value of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio, and systemic immune inflammation index in severe post-operative pulmonary infection in haemorrhagic stroke patients based on sex.</sec><sec><title>METHODS</title>This retrospective study included 193 male and 129 female patients with haemorrhagic stroke and post-operative pulmonary infection. Univariate and multivariate logistic regression models were used to determine the association between inflammatory markers from peripheral blood counts and severe pulmonary infection in these patients.</sec><sec><title>RESULTS</title>The proportions of severe pulmonary infections in male and female patients were respectively 35.8% and 24.8%, with a significant difference. Among female haemorrhagic stroke patients, the results of the multivariate logistic regression model showed that the NLR on the third post-operative day (≥9.17) was associated with severe pulmonary infection. Among male haemorrhagic stroke patients, the results of the multivariate logistic regression model showed that NLR on the first post-operative day (≥13.28) and NLR on the third post-operative day (≥8.85) were associated with severe pulmonary infection.</sec><sec><title>CONCLUSIONS</title>The predictive values of NLR for post-operative severe pulmonary infection varied among haemorrhagic stroke patients of different sexes. However, a higher NLR on the third post-operative day was associated with severe pulmonary infection in both male and female patients with haemorrhagic stroke.</sec>.