In laboratory studies on aerobic incubation of etridiazole at 20°C (two soils) and 25°C (one soil) (pH 6.0-7.4, 2.1-3.1% oc), etridiazole degraded with DT50 and DT90 values (recalculated to 20°C) of 2.22-67.9 days (mean 25.0 days) and 7.37-289 days (mean 104 days). The DT50 and DT90 values were derived from the best fit model (FOMC for the soil at 25°C and SFO for the soils at 20°C) and were corrected for volatilisation of etridiazole from soil. Hence, they represent halflives for degradation and can be used as worst case endpoints to assess persistence (under practical use conditions volatilisation of etridiazole may contribute to its dissipation from treated soil). Major metabolites (exceeding 10% AR at any time point or 5% AR at 2 consecutive time points) were etridiazole acid (maximum 31% AR on day 32) and dichloro-etridiazole (maximum 13.3% AR on day 4, including 1.3% AR volatilised dichloro-etridiazole). No other metabolite fractions >5% AR were observed. Mineralisation of etridiazole was observed in all soils: 8.2-22% AR on day 90-120 (25°C), maximum 8.7% on day 64, 4.8% AR on day 100 (soil 1, 20°C) and maximum 4.7% AR on day 100 (soil 2, 20°C). Non-extractable residues were also formed but never exceeded 70% AR: for etridiazole incubated at 25°C maximum 6.0% AR after 90 days and for etridiazole incubated at 20°C, maximum 40% and 33% AR after 100 and 32 days. Aerobic metabolism of etridiazole proceeds due to microbial processes by simultaneous hydrolysis to etridiazole acid or dechlorination to dichloro-etridiazole. The ultimate breakdown products are CO2 and non-extractable residues.