Objective: Evaluation of the use of short probes as a detection system in real-time PCR. Design and method: Comparison of results obtained with hybridization probes with and without locked nucleic acid (LNA) residues in the detection of fetal DNA in maternal serum. Results: The use of chimeric LNA/DNA probes led to a slight but significantly higher level of sensitivity as well as a higher level of fluorescence signal. Conclusion: Chimeric LNA/DNA probes offer an interesting alternative detection method in real-time PCR. (C) 2004 The Canadian Society of Clinical Chemists. All rights reserved.