Two corn. and 2 original microbicide formulations with active agents [(RRMe2NCl)-R-1-Me-2, where R-1 = R-2 = Me(CH2)(9) (I) or R-1 = n-C-12-C-16 alkyl and R-2 = PhCH2 (II)] were used for disinfection of dust and condensate samples collected in air-conditioning system. The original formulations differed from the corn. ones by addn. of ethoxylated fatty alcs., alkylpolyglycosides and chelating agents. The original microbicide formulations showed satisfactory efficiency.