The karyological analysis is an important tool for the detection of biodiversity; it is also used for measuring biodiversity evolutionary aspects. Several families of Perciformes showed a remarkable degree of chromosomal conservation (2n=48, FN=48). The present study was aimed to characterize cytogenetically the chromosomal formula, chromosome numbers and karyotypes of four fish species of order Perciformes;(Argyrosomus regius, Pomadasys stridens, Sparus aurata and Dicentrarchus labrax) collected from the Mediterranean Sea in Port Said. The Mitotic chromosomal spreads illustrated that all chromosomes of these four species are acrocentric chromosomes, the chromosomal formula for all four fish species was 48a and the fundamental number for all four fish species is (FN=48). The relative length ranged from 1.82% to 5.61% in Argyrosomus regius 2.73% to 5.61% in Pomadasys stridens, 1.91% to 5.83% in Sparus aurata and in Dicentrarchus labrax it ranged from 2.48% to 5.59%. All species had centromeric index equal zero and arm ratio equal ∞.