The purpose of the study was to determine how the waste from m-Endo agar LES (LesEndo) should be categorized and managed, due to its content of the carcinogenic substance basic red 9 in basic fuchsine. The information was obtained by studying legislation and a laboratory practical was performed to verify, if basic fuchsine could remain in LesEndo agar after being heated. This was important to know for the further interpretation how to categorize and manage the waste according to the legislation. LesEndo agar was autoclaved at 121 °C for 15 and 30 minutes. E. coli and coliform bacteria was put to grow on the LesEndo agar. The results from the study showed that all replicas had coliform colonies, which appeared with a metallic fuchsine-sheen. This verified that basic fuchsine was unchanged and that there was no significant difference in growth between replicas with heated agar and the control. The total concentration of basic fuchsine in LesEndo agar was 0.08%. To be categorized as hazardous waste the threshold value for basic red 9 is 0.1%. According to a strict interpretation of the legislation, waste from used LesEndo agar should not be categorized and managed as hazardous waste. However, evaporation has to be taken into consideration and the concentration may be above 0.1%. Therefore my evaluation is that waste from used LesEndo agar should be categorized and managed as hazardous waste to protect humans and the environment from being harmed.