Differential blood cell counts of erythrocytes and leucocytes were made of 14 specimens of 9 species of sharks and one ray, namely: Galiocerdo cuvieri, Carcharhinus leucas, C. milberti, C. obscurus, Negaprion brevirostris, Ginglymostoma cirratum, Sphyrna mokarran, S. tiburo, Rhizoprionodon terraenovae and Raja eglanteria The average measurements of mature erythrocytes of these 10 species Were also given, as well as some red cell counts.