The effect of sulphite-reduction in 33 sample bacterial strains was tested. With regard to the capacity of reducing sulphite in modified sulphite-reduction media in a wide scale of bacterial strains the possibility of an application of selective media with an addition of various concentrations of antibiotic solutions was checked. A concentration of 750 microgram of D-cycloserine per 1 ml of the sulphite-reduction medium appeared to be the most advantageous for the isolation and detection of sulphite-reductive clostridia, above all of Clostridium perfringens. This concentration ensured also a sufficient inhibition of undesirable bacteria without any affection of the growth and capacity of Clostridium perfringens to reduce sulphite in the applied medium.