In a recent paper Cohn et al. (Phys. Rev. Lett. 82 (1999) 779) report an observation of low-temperature glasslike (similar toT(2)) heat conduction in semiconductors Sr8Ga16Ge3O with type-I clathrate hydrate crystal structure. This behavior was attributed to phonon scattering by a broad distribution of two-level systems (TLS). The experiment was carried out on polycrystalline samples with typical grain size around 10 mum. Our simple estimates however show that in such a case at T < 1 K the mean free path of phonons should be limited by boundary scattering inside single grains and not by resonant scattering on TLS. Therefore we conclude that the observed low-temperature thermal conductivity might be of non-phonon origin and rather due to the long-range interaction between dopant ions of Sr in big 24-vertex polyhedral cages. (C) 2003 Elsevier Science B.V. All rights reserved.