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In this research, we observe and rationalize theoretically the transition from hexagonal to cholesteric packing of double-stranded (ds) DNA in dispersion particles. The samples were obtained by phase exclusion of linear ds DNA molecules from water-salt solutions of poly(ethylene glycol)-PEG-with concentrations ranging from 120 mg ml −1 to 300 mg ml −1 . In the range of PEG concentrations from 120 mg ml −1 to 220 mg ml −1 at room temperature, we find ds DNA molecule packing, typical of classical cholesterics. The corresponding parameters for dispersion particles obtained at concentrations greater than 220 mg ml −1 indicate hexagonal packing of the ds DNA molecules. However, slightly counter-intuitively, the cholesteric-like packing reappears upon the heating of dispersions with hexagonal packing of ds DNA molecules. This transition occurs when the PEG concentration is larger than 220 mg ml −1 . The obtained new cholesteric structure differs from the classical cholesterics observed in the PEG concentration range 120-220 mg ml −1 (hence, the term 're-entrant'). Our conclusions are based on the measurements of circular dichroism spectra, X-ray scattering curves and textures of liquid-crystalline phases. We propose a qualitative (similar to the Lindemann criterion for melting of conventional crystals) explanation of this phenomenon in terms of partial melting of so-called quasinematic layers formed by the DNA molecules. The quasinematic layers change their spatial orientation as a result of the competition between the osmotic pressure of the

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