The typical costs associated with parasitism have led to the suggestion that immunosuppression in the host may be an important mechanism mediating the life history cost of reproduction, defined as a decrease in residual reproductive value as a consequence of parental effort. More immunocompetent individuals have therefore been predicted to reveal higher fitness through more optimal reproductive decisions and increased survival. In this study, we simulated a challenge to the immune system of male and female great tits (Parus major) by injecting a novel but harmless antigen, sheep red blood cells (SRBC), and related the elicited immune response to (long-term) survival and reproductive traits, relevant to the determination of lifetime reproductive success in this species. In females, we could not detect any relationships between humoral immunocompetence and laying date, clutch size, or mean fledging mass during the breeding season following the winter period during which we assessed the immune response. Furthermore, immune response to SRBC did not predict survival of male and female great tits until the following breeding season as well as until the breeding season the year after. Overall, humoral immunological quality measured during winter did not predict important fitness components in great tits.