Background: Wine-induced asthmatic symptoms may be caused by sulphite additives. Prostaglandin (PG)D2 and cysteinyl leukotrienes (cysLT) are important mediators of asthmatic responses. To determine whether the sulphite additives in wine alter the production of PGD2 and cysLT, asthmatic patients with compelling histories of wine sensitivity were challenged with high- and low-sulphite wines; the urinary metabolites of PGD2 and cysLT were measured before and after challenge. Methods: Eight self-reporting wine-sensitive asthmatic patients completed double-blind challenges with high- and low-sulphite wines on separate days. Urine samples were collected before and after consumption of 150 ml of wine. Urinary concentrations of 9α,11β-PGF2 and leukotriene (LT)E4 were measured by enzyme immunoassay. Results: Urinary 9α,11β-PGF2 concentrations increased in all subjects following challenge with high-sulphite wine, and the median concentration increased 1.6-fold (p <0.01). Urinary 9α,11β-PGF2 also increased 1.5-fold after low-sulphite wine challenge, although this did not reach statistical significance (p = 0.08). The median difference in 9α,11β-PGF2 concentration after high-sulphite wine challenge was not significantly different compared with that after low-sulphite wine challenge. Median urinary LTE4 concentrations did not change significantly after either wine challenge. Conclusions: Increased urinary 9α,11β-PGF2 concentrations following wine challenge suggest mast cell activation as a possible mechanism for wine-induced asthma, although this did not appear to be related to the sulphite additives in wine. Urinary 9α,11β-PGF2 may warrant further assessment as a potential biomarker of reactivity to wine in asthmatic subjects.