The uterine immune axis holds the key to solving major problems in female reproductive health, including infertility, many pathologies of pregnancy, and sexually transmitted disease. The molecular determinants of tolerance and immunity in the reproductive tract are now being identified, and the governing principles are similar to those in other mucosal tissues. Cytokines are implicated as pivotal regulators at important 'decision-making' points in each phase of the induction and elicitation of a response. Indeed, the flexibility to deal appropriately with antigens as disparate as infectious micro-organisms, spermatozoa and the conceptus is likely to be attributable to the sophistication of the cytokine network in driving immune deviation. A better understanding of the factors controlling the development of immune activity in the uterus, particularly the significance of the inductive cytokine environment in determining the destiny of T-lymphocyte responses, will assist the rational design of new therapeutic strategies to treat immune-based reproductive disorders.