The present invention relates to antibodies and related molecules that specifically bind to C3a Receptor. Such antibodies have uses, for example, in the prevention and treatment of asthma, allergy, and other related inflammatory and immune disorders. The invention also relates to nucleic acid molecules encoding anti-C3a Receptor antibodies, vectors and host cells containing these nucleic acids, and methods for producing the same. The present invention relates to methods and compositions for preventing, detecting, diagnosing, treating or ameliorating a disease or disorder, especially inflammatory and other related disorders, comprising administering to an animal, preferably a human, an effective amount of one or more antibodies or fragments or variants thereof, or related molecules, that specifically bind to C3a Receptor.