There are seven species of marine turtles known throughout international waters. These are Loggerhead turtle/Caretla carelta (Linnaeus, 1758), Green turtle/Chelania mydas (Linnaeus, 1766), Kemp's ridley turtlell.epidochelys kempii (Garman, 1880), Olive ridley turtle/1,epidochelys olivacea (Eschscholtz, 1829), Flatback turtle/Natator depressus (Garman, 1880), and Leatherback turtle/Dermochelys coriacea (Vandelli, 1766).In Indonesian waters, there are six species of marine turtles. Kemp's ridley turtle is the only species from the above, which is not found.The status of the Olive ridley turtle in the Red DataBook-IUCN (International Union for Conservation of Nature and Natural Resources) is 'Endangered'. CITES (Convention on International Trade of Endangered Species of Wild Flora and Fauna) categorizes this species in `Appendix I' meaning that the trading of this animal should be limited. In Indonesia, the Olive ridley--along with the Leatherback, Hawksbill, Flatback and Loggerhead turtle--is listed as a protected species, while the Green turtle is the only turtle species not protected by regulation.Compared with other species of turtle, there is still lack of documentation concerning the Olive ridley turtle in Indonesia. So far, there is still relatively little publication about this species. The main reason is probably because of the limited knowledge of the Olive ridley nesting beach's location. For this reason, research was conducted at Pantai Marengan, in Alas Purwo National Park (Alas Purwo NP), Banyuwangi, East Java. This is one of the few known nesting sites of the Olive ridley turtle in Indonesia.The aim of the research was to investigate the nesting of the Olive ridley turtle. A study of morphometrics and captive program in Alas Punvo NP was also made as part of the research. It is hoped that, the results will be useful for the conservation of the turtle and its habitat.The research was performed during the turtle's nesting season, between March and October 1995. During this period, one hundred and sixty-two (162) nests were found. The peak of activity occurred in July, when fifty-one (51) nests were located. The average clutch size was one hundred and four (104) eggs per nest. On average, the nests were located 5.8 m (SD = 6.7) from vegetation and 18.5 m (SD = 11.5) from the highest high tide mark. The morphometric study of thirty (30) nesting turtles showed that the average curved carapace measurements were 67.5 cm in length (SD = 3.2) and 66.7 cm in width (SD 3.9). The results of carapace measurements showed that the carapace length positively correlated with carapace width, i.e., as the carapace length increase, so the carapace width will also increase. No correlation was found between carapace length and the number of eggs in each clutch. There was also no correlation found between the number of eggs laid and the time used for nesting activity.The captive program of Olive ridley turtle in Alas Purwo NP was set-up in 1989. The survival percentage of hatchlings from semi-natural hatching recorded during the 1995 season was 83.7 %. The highest hatching death rate (45.3 %) occurred in August, when temperature in the rearing container fell to 20"C.According to the secondary data, during the 1984/1985 nesting season, only three (3) nesting sites of the Olive ridley turtle were found in Alas Purwo NP. In the period between April and June 1996, however, one hundred and sixty-nine nesting sites were located. Is population of the Olive ridley turtle increasing within the Alas Purwo NP? The question can only be answered more accurately by tagging of individual animals and monitoring the species over a longer term.