Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that plays important roles in allergic responses including asthma. S1P acts on many cell types, such as mast cells, the airway epithelium, airway smooth muscle and many immune cells. In this study we have evaluated if a systemic administration of S1P to Balb/c mice modifies airway reactivity. Our data show that S1P (0.1-10ng) given s.c. to Balb/c mice causes a specific and dose dependent increase in cholinergic reactivity of bronchial tissues in vitro. This effect is i) dose dependent, with a maximal effect of the dose of 10ng of S1P; ii) time dependent, reaching a maximal effect 21 days after S1P administration. Similarly, in the whole lung assay there is a dose and time dependent increase in lung resistance. Lungs isolated from S1P-treated mice displayed an increase in mast cell number. Furthermore there is an increase of IL-4, IL-13 and IL-17 production. In conclusion our data demonstrate that S1P signalling is involved in the complex pathway underlying airway hyper-responsiveness.