In the past decade, the popularity and power of Tissue Microarray (TMA) technology has increased since it provides a method to detect diagnostic and prognostic markers in an array of clinical tissue specimens collected for translational research. TMAs allow for rapid and cost-effective analysis of hundreds of molecular markers at the nucleic acid and protein levels. This technology is particularly useful in the realization of the Human Protein Atlas Project, since it aims to create a reference database of non-redundant human proteins. In this context, it is important to assure the lack of cross-sample contamination due to the repeated use of the same needle in consecutive coring. Here we show that carry-over contamination from one tissue core to another does not occur, reinforcing the accuracy of the TMA technology in the simultaneous testing of multiple bio-samples.