Some base line hematological data obtained from 50 rodents collected from uncontaminated control areas off-site are presented. These data will be used as a basis for comparison with blood values obtained from resident animals of NAEG intensive study areas. Possible future plans are discussed, such as reducing the number of continuous study areas, and intensifying the investigation of certain areas to include preliminary observations on the availability of Pu and Am in rodent burrows. INTRODUCTION Ecological studies of vertebrates in the three Pu-contaminated areas of NTS began in spring, 1972, and were expanded to include four areas of TTR in fall, 1973. During the initial phases of this study, emphasis was on the development and improvement of standardized procedures for inventory, census, and collection of small vertebrates. This methodology is discussed in previous reports (Moor and Bradley, 1974; Bradley and Moor, 1975). This report includes analysis of data obtained during the contract period from the continuous study of seven areas of NTS and TTR. In addition, hematological studies of lizards and rodents began in fall, 1974. Emphasis during the report period has been on collecting vertebrates from areas off-site to obtain base line hematological data for comparisons with data which will be gathered from resident vertebrates of NAEG intensive study areas in the summer of this year. MATERIALS AND METHODS Census Methods Various standard census methods were employed to obtain a qualitative and quantitative inventory of the vertebrate biota in each NAEG 54