Lithium fluoride powder incorporated into a Teflon matrix allows the fabrication of dosimeters which combine ease of handling and readout with reproducible sensitivity. The properties of such LiF-Teflon dosimeters have been investigated. Especially, we have studied thin disks, 12.5 mm diameter by 0.13 to 0.5 mm thickness, containing 25 per cent LiF, and rods, 1 mm diameter by 6 mm length, containing 8 per cent LiF. Fabrication of other shapes of dosimeters is possible. The 12.5 mm diameter disks allow measurements from about 50 mR, with a precision of about ± 15 per cent (standard deviation). The variations at this dose level are caused mostly by variations in the dark current of the photomultiplier used. The 6 mm rods can be used down to 3 R, with a precision of ± 20 per cent. At higher doses, for the disks from 3 R to 105 R and for the rods from 50 R to 105 R, the precision is ±3 per cent. The LiF-Teflon dosimeters can be re-used after the proper annealing heat treatment. Washing and sterilizing cause no change in their sensitivity. The characteristics of LiF thermoluminescence are not affected by the presence of the Teflon matrix. In particular, the glow curve is the same as that of loose powder, as is the curve of thermoluminescence-light-sum vs. exposure. The favorable energy dependence of LiF is modified very little by the Teflon—the effective atomic numbers of LiF and Teflon are 8.2 and 8.4, as compared to 7.42 for muscle tissue. The dose build-up in a Lucite block exposed to a collimated Co60 gamma-radiation beam has been measured with LiF-Teflon disks. The surface dose was 50 per cent of the dose at electron equilibrium. Similar results were obtained with the rod. Disks placed between sheets of various metals were irradiated with Co60 gamma radiation. The results show that the dosimeters work well as a truly dose-measuring detector when placed in a medium irradiated with photons of 1 MeV or higher energies. The rods are suitable for dose measurements when small detector size is essential, as when determining dose distribution from radioactive implants or applicators. Rods of only 2 mm in length can be used; or a long rod can be irradiated, then divided into smaller pieces, and the dose received by each piece measured. A flexible long rod is easy to recover after in vivo measurements. The LiF-Teflon dosimeters can be employed equally as well for beta and electron as for photon dosimetry. Several problems in radiological dosimetry, which have been difficult to study with other types of dosimeters, can be investigated with these LiF-Teflon dosimeters, e.g., depth-dose distributions, electron build-up, and skin-dose measurements. Their rug-gedness and reproducibility open up possibilities for applications in routine dosimetry, such as intracavitary and surface dose measurements, and measurements with the dosimeters directly in tissue.