Abstract Quantitative study of the ostracode assemblages from the Palaeocene to Early Eocene succession exposed along the area of east-central Sinai extending from the Egma Plateau in the south to Areif El Naqa in the north, using cluster analysis based on the customary presence/absence data matrix of frequencies (the Jaccard coefficient of similarity), has resulted in the distinction of five ecozones in the Early Palaeocene to Early Eocene intervals. Correspondence analysis applied to the same data matrix has led to the identification of five environmental factors affecting the distribution of the whole ostracode assemblage of the study area. These are the time factor or vertical distribution (second latent vector), water depth (third latent vector), degree of energy (fourth latent vector), water temperature as a function of depth (fifth latent vector), and oxygen concentration (sixth latent vector). From this, the prevailing palaeoenvironments in the study area during the Early Palaeocene to Early Eocene times have been reconstructed. A distinct faunal change has been detected at the Palaeocene-Eocene thermal maximum (PETM) as indicated by the second latent vector.