Background: Bronchial asthma patients may develop various asthmatic response types to bronchial challenge with allergen, such as immediate (IAR), late (LAR), dual (DAR) or delayed (DYAR), due to different immunologic mechanisms. The DYAR, beginning between 26-32 hrs and lasting up to 56 hrs after the allergen challenge, differs from the IAR, LAR and DAR in clinical, diagnostic and immunologic aspects. The aim of this study was to investigate the concentrations of the particular intracellular cytokines released by blood cells stimulated with relevant allergens “in vitro”, before and during the DYAR. Methods: In 23 patients, the repeated DYAR (p < 0.001) was supplemented with cytokine determination in the supernatants of the blood cells stimulated with relevant allergens before and up to 72 hours after the bronchial challenge, by means of enzyme-linked immunoassay. Results: The significantly elevated pre-challenge concentrations (p < 0.05) of IL-2, IL-17, IFN-γ and G-CSF released by allergen-stimulated blood cells “in vitro” were recorded in the DYAR patients as compared with healthy controls. The significantly increased post-challenge concentrations (p < 0.05) of IL-1β, IL-2, IL-8, IL-12p70, IL-18, IFN-γ and TNF-α, whereas decreased concentrations of IL-4, IL-6 and IL-17, were released by blood cells stimulated with relevant allergens “in vitro”, as compared both with their pre-challenge concentrations and with the corresponding PBS control values. Conclusions: The profiles of cytokines released by allergen-stimulated peripheral blood cells during the DYAR would suggest an activation of Th₁ cells, neutrophils, monocytes and probably also bronchial macrophages, epithelial and endothelial cells and their involvement in the immunologic mechanism(s) underlying the clinical DYAR.