Two matching groups each of eleven patients suffering from allergy to Parietaria pollen were treated either with tyrosine-adsorbed glutaraldehyde-modified extract of Parietaria judaica pollen (Bencard Parietaria/Pollinex Parietaria) or with alum-adsorbed pyridine-extract (Alavac). The side effects of therapy were similar in both groups and were mostly local in nature. Nasal symptoms were significantly less at the end of treatment in the group of patients treated with Pollinex. P. judaica-specific IgG levels were significantly higher in patients following treatment with Pollinex. The majority of patients in both groups showed reduced nasal and/or skin sensitivity following therapy as measured by provocation testing. The results indicate that Pollinex Parietaria is an effective vaccine for the treatment of immediate hypersensitivity to Parietaria pollen.