An inexpensive procedure that uses small volumes (5-10 ml) of cell culture for the rapid isolation of restriction enzymes, sufficiently pure to allow preliminary characterisation, is presented. The method was designed initially to screen for Type II restriction enzymes, but different assays can be devised to screen for other types of restriction enzymes. Although initially optimised in Lacotococcus lactis subsp. cremoris LC17-1, this method potentially holds wider applications in other lactococcal species as was shown by its successful application to Lactococcus lactis subp. lactis. Without the necessity for chromatographic techniques that are often expensive and time consuming, the convenience of the technique makes it suitable for rapid, routine screening of a large number of lactic acid bacterial strains, or restriction and modification systems cloned into them, for restriction enzyme activity.