Heavy metal contents of aquatic biofilms isolated from stones collected from, and ceramic plates exposed in, the River Elbe were determined by total-reflection X-ray fluorescence spectrometry (TXRF). The fractions of several elements (K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Pb) referred to the dry mass are 100 to 60 000-fold higher in the biofilm matrix compared with the bulk water phase. Biofilms grown on the exposed plates have a mass fraction of the determined elements higher by a factor of 2–3 compared with the biofilms derived from stones. These differences may be attributed to the different ages of the biofilms.