The impact of high pollen load of particular plants on sensitized subjects is a topic of interest. We aimed to detect the clinical importance of poplar allergy in subjects with seasonal allergy living in Ankara, capital city of Turkey, having a high poplar pollen load. The subjects with seasonal allergy and demonstrating allergy to Populus alba in skin-prick tests (SPTs) (n = 20) underwent a specific nasal provocation test with P. alba allergen extract and were requested to fill in symptom-medication reports. During the same period, P. alba and Gramineae pollen counts were assessed in the city. Pollination for P. alba in Ankara for the year 2001 started in the 2nd week of March and terminated in the 1st week of May; 96.5% of subjects also had grass pollen sensitivities. By history, 85% of the subjects described mild symptoms in March and April, the expected pollinosis season for P. alba. Symptom and medication scores were higher in May and June than in March and April (p < 0.05). Allergy to P. alba pollen in patients with seasonal allergy causes mild symptoms where the dominant clinical presentation was demonstrated to be due to their additional Gramineae (grass) pollen allergy.