On the basis of the fluorescence enhancement effect of nucleic acids on the aluminum (III) / 8-hydroxyquinoline (8-HQ) complex, a spectrofluorimetric method for nucleic acids is proposed in the present paper. In the pH range 5.8–7.0, the fluorescence of the Al(III)/8-HQ complex, excited at 265 nm or at 365 nm, is enhanced by nucleic acids. The calibration curve was linear in the range 0.25 – 3.0 μg ml−1for calf thymus DNA, 0.25 – 3.5 μg ml−1for fish sperm DNA and 0.5 – 3.5 μg ml−1for yeast RNA, respectively. The limit of determination (3[sgrave]) was 0.024 μg ml−1for calf thymus DNA, 0.013 μg ml−1for fish sperm DNA and 0.130 μg ml−1for yeast RNA, respectively. Six synthetic samples were determined with satisfaction.