The Miocene reef limestones in Israel (Ziqlag Formation) are of Tortonian (Upper Miocene) age. They form the transgressive part of a sedimentary cycle which was terminated by the Messinian desiccation events in the Mediterranean. The biogenic and clastic constituents of calcarenitic limestones in the Ziqlag Formation were studied in detail. Using multivariate techniques (cluster and association analysis) based on quantitative and semi-quantitative data, the limestones were subdivided into three main groups corresponding to three depositional facies: 1) coral reef, 2) backreef platform, 3) beach and nearshore. The most characteristic constituents of the reefs besides corals are encrusting foraminifers. Backreef platform limestones are relatively enriched in other foraminifers, especially of the miliolid-rotaliform- Amphistegina assemblage. Beach and nearshore sediments are depleted in foraminiferal constituents and consist mainly of molluscan and echinoid debris. Detailed analysis is given of outcrops in the Ofaqim, which are representative occurrences of coral reefs, and of outcrops in the Ziqlag hills, which are representative of backreef platform and beach facies. The fauna of the Ziqlag reef complex is impoverished compared with both Holocene tropical reefs and other Early Miocene reefal occurrences in the Tethys area. The decline in coral and other biota is attributed to gradual cooling toward the end of the Miocene. Diagenetic processes affecting the reef complex include: 1) recrystallization of the aragonite and high-Mg calcite elements to low-Mg calcite which is the case in most of the samples, 2) dolomitization which is rare and is most conspicuous in the Ofaqim forereef belt, whereas the reef core escaped dolomitization. High-Mg calcite elements such as coralline algae and micritic envolopes were preferentially dolomitized, whereas echinoid fragments resisted dolomitization and were leached out.