The development of molecular diagnostic methods, particularly those utilizing PCR for the detection of parasitic protozoa will contribute greatly to the identification and control of these pathogens, by increasing speed of diagnosis, specificity and sensitivity, reproducibility and ease of interpretation. PCR methods are not without their problems however, and there is a need for laboratory procedures to be refined before PCR-based assays are accepted as the tools of choice for the routine detection of protozoan parasites. The application of PCR detection to various parasites is discussed.