Background. Monitoring treatment response in invasive aspergillosis is challenging, because an immunocompromised host may not exhibit reliable symptoms and clinical signs. Cytokines play a pivotal role in mediating host immune response to infection; therefore, the profiling of biomarkers may be an appropriate surrogate for disease status. Methods. We studied, in a cohort of 119 patients with invasive aspergillosis who were recruited in a multicenter clinical trial, serum interleukin (IL)-6, IL-8, IL-10, interferon-γ, and C-reactive protein (CRP) trends over the first 4 weeks of therapy and correlated these trends to clinical outcome parameters. Results. Circulating IL-6 and CRP levels were high at initiation of therapy and generally showed a downward trend with antifungal treatment. However, subjects with adverse outcomes exhibited a distinct lack of decline in IL-6 and CRP levels at week 1, compared with responders (P = .02, for both IL-6 and CRP). Nonresponders also had significantly elevated IL-8 levels (P = .001). Conclusions. High initial IL-8 and persistently elevated IL-6, IL-8, and CRP levels after initiation of treatment may be early predictors of adverse outcome in invasive aspergillosis. Cytokine and CRP profiles could be used for early identification of patients with a poor response to antifungal treatment who may benefit from more-aggressive antimicrobial regimens.