Objective Despite the potentially life-saving effects of stem cell transplant (SCT), many transplant patients experience traumatic stress reactions due to mortality threat, interpersonal isolation, financial and occupational loss, and invasive medical procedures. Emerging evidence suggests that trauma-related stress symptoms (TSS) predict significant health complications following SCT. The aim of the current prospective study was to examine TSS in the acute aftermath of SCT as a predictor of neutrophil recovery following SCT, a crucial component of immune defense against infection. Methods Fifty-one autologous SCT recipients were assessed for TSS 7 days after SCT. Patients' absolute neutrophil counts were collected from medical charts for the first 30 days following SCT. Hierarchical linear growth modeling was used to test the hypothesis that TSS at day 7 would be associated with delayed recovery of neutrophil counts from days 9 to 30 post SCT, that is, when neutrophil counts began to recover. Results As hypothesized, TSS measured 7 days after SCT was significantly associated with slower neutrophil recovery even after pre-existing TSS, depression, distress related to physical symptoms, and potential medical confounds were statistically controlled. Exploratory analyses showed that of the TSS symptom clusters, re-experiencing symptoms and hyperarousal symptoms predicted neutrophil recovery, whereas avoidance symptoms did not. Conclusion Though traumatic stress symptoms may be a normative response to SCT, our findings suggest that TSS following SCT may interfere with neutrophil recovery and overall health. These results provide further insight as to potential mechanisms by which traumatic stress translates to poor medical outcomes for SCT patients.