We assessed the clinical effectiveness and adverse effect of various types of immunotherapy on 42 pollinotic patients by monitoring their evolution on administration of Perennial lolium specific extract standardized in protein nitrogen units to 14 of them, the same extract but standardized in biological units (BUs) to another 13, and an extract containing four different pollens standardized in BUs to the remaining 15. For this purpose we measured clinical and medicinal scores, liver and kidney biochemical parameters, skin reactions and circulating immunocomplexes (CICs), both before immunotherapy was started (basal levels) and after 3, 6 and 12 month's treatment. We found no significant differences in clinical effectiveness or the occurrence of any adverse effects on administration of the different immunotherapies after one year's monitoring. We did found gradually decreased reactions to the skin tests, which thus provide a reliable means of monitoring allergen-specific immunotherapy.