The ability of organophosphate pesticides to disturb immune function has been demonstrated by in vivo and in vitro studies, but evidence of such effects on humans remains scarce. To assess the association between organophosphate pesticides exposure and cytokine levels in Mexican flower workers, a cross-sectional study was carried out. A questionnaire was provided to 121 male flower workers, and urine and blood samples were collected. Using gas chromatography, urinary concentrations of dialkylphosphate metabolites were determined. The serum cytokine levels, IL-4, IL-5, IL-6, IL-8, and IL-10, were measured using multiplex analysis, and levels of INF-γ and TNF-α by ELISA. We found that a higher dialkylphosphate concentration decreased the pro-inflammatory cytokines INF-γ (β = −0.63; 95 % CI: −1.22, −0.05), TNF-α (β= −1.18; 95 % CI: −2.38, 0.02), and IL-6 (β= −0.59; 95 % CI: −1.29, 0.12), and increased IL-10 (β=0.56; 95 % CI: 0.02, 1.09), the main anti-inflammatory cytokine, suggesting an imbalance of the immune response in flower workers.