There are limited data regard-ing immune surveillance mechanisms in ol-factory neuroblastoma. We investigated the expression of programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), CD4, and CD8 in olfacto-ry neuroblastoma to identify potential ther-apeutic targets. Immunohistochemistry was used to detect PD-1 and CTLA-4 and mea-sure the numbers of CD4+ and CD8+ T cells in 56 patients with olfactory neuroblastoma. The relationships between these molecules in tumor microenvironment, clinicopatho-logical features, and survival were analyzed. The prevalence of PD-1 in Kadish C stage was 24.14%, significantly greater than in Kadish A and B stage. CD4+T-cell and CD8+T-cell lev-els correlated with higher Hyams histologi-cal grade and Kadish stage. In addition, PD-1 was related positively with CTLA-4, CD4+ T cells, and CD8+T cells in olfactory neuroblas-toma. Univariate survival analysis showed that higher PD-1 positivity, CD8+T cells, and Hyams grade correlated with worse clinical outcome. Multivariate analysis showed that the expression of PD-1 was an independent parameter for poor prognosis. In conclusion, olfactory neuroblastoma with PD-1 expres-sion had more aggressive clinicopathologi-cal features and worse prognosis. PD-1 may potentially predict the outcome of olfactory neuroblastoma patients.