The import of LiF dose measurements at depths within phantoms and patients depends upon their agreement with traditional ionization chamber measurements. The lack of correlative depth-dose studies utilizing both measurement technics is surprising, since increased response of LiF at low photon energies (1) may provide inaccurate dose measurements in degraded photon beams. Ionization chamber and LiF dose measurements at depths within phantoms exposed to orthovoltage x-ray and 60Co radiation have been compared in our laboratory. Cobalt-60 depth doses measured with TLD-100 LiF agree well (± 1 per cent) with ionization chamber measurements. A single exposure to LiF within polyethylene capsules spaced at 1-cm intervals along the beam central axis provides convenient depth-dose curves. Curves for different 60Co fields measured by this technic agree well with those obtained with a small ionization chamber. Presence of LiF capsules at shallow depths does not noticeably perturb the dose at any point along the centr...