Allergy to pine trees is generally held to be rare and clinically insignificant. Skin test sensitivity to pine pollen antigen was found in 12 of approximately 826 (1.5%) atopic patients in a northern Arizona private allergy practice. There were five women and seven men and their ages ranged from 6 to 59 years. All were residents of the pine tree area for at least 2 years. All 12 reacted to the antigen of the predominant ponderosa pine and five also reacted, usually less strongly, to Colorado pinyon pine. Eight patients had spring season rhinoconjunctivitis and four others had perennial symptoms. Four of the 12 also had asthma. Some patients had clinical symptoms coinciding with pine pollen season.