Set amalgam, annealed for twelve days, was cut with water cooling and sucked into eight dental units (Systematica 1062 T), equipped with an amalgam separator (Multisystem Type 1). Disinfection of the suction devices was performed with seven commonly used disinfectants according to the manufacturer's guidelines. Rinsing with water served as a control in the last experimental series. The waste water was collected at the beginning of the experiments and after disinfection. Repeating the experiments for seven times resulted in 112 specimens that were analyzed by atomic absorption spectrophotometry. The use of Green & Clean M2 and S & M matic resulted in very low releases of mercury. Disinfection with Alprojet D and Alprojet DD M2 was comparable with the control group. The release of mercury was significantly increased, if compared to Green & Clean and S & M matic (p < or = 0.05). The use of Orotol Ultra, Aseptoclean 2, and Tiutol resulted in significantly higher releases of mercury, if compared to all other disinfectants (p < or = 0.05). Disinfectants containing oxidizing agents provoke an increasing release of mercury, thus accumulating the amounts of mercury in the general environment.