1. 1.Both Helicops modestus and Liophis miliaris. Brasilian water snakes with different degrees of aquatic adaptations, present 3 haemoglobin components identified by starch-gel electrophoresis and separated by DEAE-Sephadex A-50 and CM-cellulose chromatography respectively. 2. 2.Some functional properties of their haemoglobins were determined. Both the oxygen affinity 1.0mmHg at pH 7) and the alcaline Bohr effect value (-0.07) of the stripped haemoglobins of the more aquatic species H. modestus were higher than those of L. miliaris (1.4mmHg and -0.30 respectively). 3. 3.The ATP effect on both haemoglobin-oxygen affinity and Bohr effect was more pronounced in L. miliaris haemoglobins. The values found were 17.8mmHg at pH 7 and -0.9; in H. modestus. they were 8.93 mmHg and -0.55. 4. 4.Nucleotide triphosphate concentrations were determined as 2.84 mmHg in H. modrstus and 2.65 mM in L. miliaris (whole blood); haemoglobin concentrations were 6.14mM and 4.21 mM (as haem), respectively. The physiological implications of these results are discussed. © 1979.632285289Andersen, Physiological adaptations in diving vertebrates (1966) Physiol. Rev., 46, pp. 212-243Antonini, Brunori, Hemoglobin (1970) A. Rev. Biochem., 39, p. 977Crenshaw, Jr, Variation in the serumffims and other blood proteins of turtles of the Kinostenidae (1962) Physiol. Zool., 35, pp. 157-165Dessauer, Fox, Ramirez, Preliminary attempt to correlate peper-electrophoretic migration of hemoglobins and phylogeny in Amphibia and Reptilia (1957) ArchsBiochem. Biophys., 71, pp. 11-16Dessauer, Fox, Electrophoresis in taxonomic studies illustrated by analyses of blood proteins (1964) Taxonomic Biochemistry and Serology, pp. 625-647. , C.A Leone, Ronald Press, New YorkFitch, Reproductive cycles in lizards and snakes (1970) Univ. Kansas Mus. Nat. Hist. Misc. Publ., 52, pp. 1-247Gorman, Dessauer, Hemoglobin and transferrin electrophoresis and relationships of island populations of Anolis lizards (1965) Science. N.Y., 150, pp. 1454-1455Hiatwole, Seymour, Diving physiology (1975) Biology of Sea Snakes, pp. 289-327. , W.A Dunson, University Park Press, BaltimoreJohansen, Lenfant, Comparative approach to the adaptability of O2—Hb affinity (1972) The Fourth Alfred Benson Symposium: O2 Affinity of Hemoglobin and Red Cell Acid Base Status, pp. 750-780. , P Astrup, M Rorth, Munhksgaad, CopenhagenLamprecht, Trautschold, Adenosine-5-triphsphate. Determination with hexokinase and glucose 6-phosphate dehydrogenase (1965) Methods of Enzymatic Analysis, pp. 543-551. , H.U Bergmeyer, Verlag-Chemie, Berlin. Academic Press, LondonLaurent, Killander, A theory of gel filtration and its experimental verification (1964) Journal of Chromatography A, 14, pp. 317-330Lenfant, Johansen, Torrance, Gas transport and oxygen storage capacity in some pinnipeds and the sea otter (1970) Respir. Physiol., 9, pp. 277-286Nakamura, Das mehrfache hämoglobin. III. Amphibien und Reptilien (1960) Lymphatologia. Kyoto, 4, pp. 52-59Neil, Viviparity in snakes some ecological and zoogeographical considerations (1964) The American Naturalist, 98 (898), pp. 35-55Ogo, Propriedades functionais de hemoglobinas de serpentes corn diferentes graus de adaptação morfológica ao ambiente aquático (1977) Doctorate thesisParker, (1965) Natural history of snakes, , British Museum. (Natural History), LondonRabb, Marx, Major ecological and geographic patterns in the evolution of colubrid snakes (1973) Evolution, 27, pp. 69-83Rodnan, Ebaugh, Paper electrophoresis of animal hemoglobins (1957) Proc. Soc. exp. Biol. Mod., 95, pp. 397-401Rossi-Fanelli, AnT́onini, Studies on oxygen and carbon monoxide equilibria of human myoglobin (1958) Archs Biochem. Biophys., 77, pp. 478-492Seymour, Webster, Gas transport and blood acid-base balance in diving sea snakes Journal of Experimental Zoology, 191, pp. 169-182Smithies, An improved procedure for starch-gel electrophoresis: Further variations in the serum proteins of normal individuals (1959) Biochem. J., 71, pp. 585-587Sullivan, Riggs, Structure, function and evolution of turtle hemoglobins. II. Electrophoretic studies (1967) Comp. Biochem. Physiol., 23, pp. 449-458Sullivan, Riggs, Structure, function and evolution of turtle hemoglobin. III. Oxygen properties (1967) Comp. Biochem. Physiol., 23, pp. 459-474Sydenstricker, Oliver, Chandler, Sydenstricker, Electrophoretic behavior of some animal hemoglobins (1956) Proc. Soc. exp. Biol. Med., 93, pp. 396-397