We have compared a new FIA method (M1) for aluminium speciation in natural waters and a manual one based on one of Driscoll's proposals (M2). In synthetic solutions, aluminium's fluoro complexes were measured as ‘labile monomeric AP (Ali) by M2, but not as ‘quickly reacting Al’ (Alqr) by M1. Aluminium's complexes with Nordic Reference Humic Acid were measured neither as Ali nor as Alqr, and the same result was obtained for Al's citrato complexes. After excluding aluminium's fluoro complexes from Ali, the results of the two methods agreed well for soil leaching samples and fairly well for natural water samples. Detection limits: 10μg L−1 (ca. 0.4 μM) for both methods. Sample throughputs: M1∶66 injections h−1; M2∶5 samples h−1. Repeatabilities (RSD) on natural water samples: M1∶0.6–5.8% and M2 0.7–4.6%.