Stylar canal cells of Lilium longiflorum were labeled before pollination with 5-(3)H-uridine or 5-(3)H-orotic acid dissolved in water, or the stylar canal was filled 6 hr after pollination with stigmatic exudate supplemented with 5-(3)H-uridine, 2-(14)C-uridine or H3 (32)PO4. Nucleic acids extracted from compatible and incompatible pollen tubes grown in these styles were separated by methylated albumin kieselguhr column chromatography. Label occurred in all portions of the RNA profile, but no label appeared in the DNA peak. Using 5-(3)H-uridine, pollen tubes of different genotype had different labeling patterns.