The temporal variations of coral zooxanthellae populations were studied in six sites at Sharm El-Sheikh area, Northern Red Sea, on four scleractinian species (Acropora humilis Dana, Pocillopora verrucosa L., P. damicornis Ellis and Solander, and Stylophora pistillata Esper). For this purpose, coral samples were collected monthly from March 2001 to May 2002. In addition, other fourteen sites were chosen along the Egyptian Red Sea reefs to determine the spatial variations of the coral zooxanthellae population. Samples for this purpose were taken during October 2002 from a similar depth contour of 5m at all sites. The population densities of coral zooxanthellae varied widely from coral species to other. The highest zooxanthellae density was recorded in the tissue of the coral A. humilis (annual average: 1.529 × 106 cell/cm2) and the lowest occurred in the tissues of the coral S. pistillata (annual average: 0.649 × 106 cell/cm2). The maximum densities of zooxanthellae in the four coral species were recorded at sites with moderate Secchi disk reading and TSS. However, the minimum densities of coral zooxanthellae were recorded at sites with Secchi disk readings and TSS exceeded than 5.75 m and 147.5 mg/L, respectively. Concerning the seasonal variations, the maximum zooxanthellae densities in the four coral species were recorded during the period of late autumn-early winter, while the minimum densities were counted during summer.