The process of developing a conservation programme for endemic plant species, in particular those with a small geographical size in mountain ecosystems, whether in situ of ex situ, is a very complex matter, especially if data on the state of the environment and conservation are unavailable. Silene leucophylla and Silene oreosinaica are perennial plants endemic to St. Catherine Protected Area (SCPA), which locate at South Sinai, Egypt. For long time, the second species has not been observed in the field. As a result, the purpose of this study was to increase understanding of the two species' ecological and conservation statuses by: The first step is to confirm their existence on the ground; the second step is to determine the present ecological and conservation conditions through an extinction risk assessment by using IUCN Red List methodology; and the third step is the use of Species Distribution Model (SDM) to locate and extract current appropriate habitat suitability. The field research, which was conducted between March to December 2017, resulted in building knowledge of the current distribution, characteristics of current species populations, and status of ecology and habitat, in addition to identifying the main threats. Both species have been recorded in 20 major sites, in a very restricted area, particularly in a high mountain region (19 sites of Silene leucophylla and 3 sites of S. oreosinaica), with Extent of Occurrence about 468.2 km2 for Silene leucophylla and 24.5 km2 for S. oreosinaica. The population size was very small and fragmented and the extreme drought and overgrazing clearly affected both species. Based on the collected data, the extinction risk was calculated as Critically Endangered for S. oreosinaica and as Endangered for S. leucophylla according to IUCN Red List. For both species, appropriate habitat is concentrated in the high mountain ranges in the central north section of the SCPA, according to SDM. For Silene leucophylla, a presence probability of 20.5 km2 was anticipated, whereas for S. oreosinaica, a presence probability of 62.1 km2 had been predicted. Conservation methods are advocated both in situ (via recovery) and ex situ (by seed collecting and storage, awareness building, and grazing control).