We compared four brands of microtubes with respect to their suitability for long-range polymerase chain reactions (PCRs). One of the four brands was found to have an inhibitory effect, decreasing PCR yields. The effect was universal across different PCR or enzyme systems. Increased ultraviolet absorbance suggests leaching of unknown chemical species into PCR mixtures. However, this could not be confirmed by high-performance liquid chromatography-mass spectrometry analysis. Nevertheless, our article demonstrates a clear impact of the choice of microtubes on long-range PCR success. Due consideration should be given to the PCR microtubes when determining optimal reaction conditions for long-range PCR.