Cyanuric acid in high concentrations (15.5 mM) was degraded completely by Pseudomonas sp. NRRL B-12228 independently of glucose concentration. In the batch fermentations there was a relation between the glucose concentration, on the one hand, and the liberation of ammonia or production of protein, on the other. The greater the supply of carbon, the more biomass was produced, and fewer NH4+ ions were released. Continuous fermentations using adsorbed cells could be performed to degrade cyanuric acid. In spite of different glucose feeding there was only a negligible difference in residues of s-triazine. In a one-step continuous system with dilution rates between 0.021 h(-1) and 0.035 h(-1), even a ratio of 0.65 between glucose and cyanuric acid was Rot sufficient to degrade the cyanuric acid supplied (320-540 mu mol l(-1) h(-1)) completely. When a continuous two-step system was applied with dilution rates between 0.035 h(-1) and 0.056 h(-1), the consumption of carbon source could be minimized while s-triazine degradation up to 860 mu mol l(-1) h(-1) was complete. In this way the ratio between glucose and cyanuric acid could be increased to 0.25 (molar C:N ratio = 0.33:1). Thereby the process was made considerably more economic.