AbstractDue to their small mass, adjacent protons (or H‐atoms) of molecular systems may exhibit quantumentanglement(or quantum correlations), even at ambient conditions. The considerable thermal disturbance and/or manybody interactions of condensed matter and the associateddecoherenceeffect, however, cause this protonic entanglement to be restricted in space and time. Some aspects of entanglement and decoherence are mentioned. Extending our previous theoretical work, in the present paper the focus is on the possible existence of entangled protons belonging to the H‐bonds ofadjacentbase pairs of B‐type DNA. Based on the ‘working hypothesis’ that this effect does really exist, the most probable ‘positions’ for the appearance of protonic entanglement in DNA sequences are qualitatively determined. Furthermore, these ‘positions’ appear to correspond uniquely to dimers of adjacent base pairs of DNA. As a consequence, one can straightforwardly search for an enhanced appearance of such entangled H‐bonds in DNA sequences of living organisms, using the existing DNA databases. A quantitative analysis of protein‐coding DNA sequences of various organisms has been performed, the results of which provide strong evidence for the existence of the considered effect. The most striking finding may be summarized as follows: Quantum entanglement appears preferably between the third base of a codon and the first base of the following one. Quantitative estimates of this and further obtained results are presented. It is also shown that quantum‐chemical considerations of stacking energies cannot account for the results. The new findings provide first evidence for the biological significan