Rye pollen was incubated for 30 min and proteins extracted at this time were collected as extract A (EA). The same pollen grains were resuspended in buffer and incubated for 18.5 h. Proteins extracted in this period were designated extract B (EB). Both extracts were subfractionated by DEAE ion-exchange chromatography and allergen presence in peaks detected by the dot-immunobinding technique. The results reveal that unretained proteins (peaks 1 and 2) and proteins eluted at 0.2 M NaCl from extract B contain the highest proportion of allergens. SDS-PAGE of chromatographic peaks showed that peak 2 from extract B contains a highly purified 28 kDa band. On the skin of allergic patients this band gave a stronger positive prick test than for the crude extract.