The present invention relates generally to novel recombinant polypeptides of Bahia grass pollen and to genetic sequences encoding same. More particularly, the present invention is directed to Pas n 1 polypeptides and derivatives, and fragments thereof and genetic sequences encoding same. The molecules of the present invention are useful in a range of therapeutic, prophylactic and diagnostic applications including, but not limited to, applications in the context of conditions characterized by an aberrant, inappropriate or otherwise unwanted immune response to the Bahia grass pollen.