With funding from the European Commission, a consortium of members of the European Water Research Institutes is carrying out a programme of work with the objective of optimising and standardising a method for determining the presence in water of (oo)cysts of Cryptosporidium and Giardia. Each of the stages of the conventional analysis procedure (initial concentration, recoveryand identification and enumeration) are being investigated and the relative merits of existing and new methods are being assessed. Newly developed filters (Envirochek and Filta-Max) have been shown to be more efficient for initial recovery of (oo)cysts from water than the previously used Cuno cartridge filters. In addition, for the analysis of raw waters, flocculationwith ferric sulphate has been shown to give recoveries similar to the Envirochek and Filta Max. Modern purification systems such as immunomagnetic separation have also been assessed and found to offer some advantages over flotation although optimisation of the latter has brought improved efficiency. Preliminary assessment of solid phase cytometry has indicated that this technique could offer significant time savings compared to conventional microscopic counting. The results of the study will be used to propose a revised standard method to CEN.