A monograph titled Physiological and biochemical adaptation of C3 and C4 plants to drought stress co-authored by the late academician J.A.Aliyev, vice president of ANAS I.M.Huseynova, correspondent member of ANAS N.M.Guliyev and leading research fellow of the laboratory of Enzymology of Photosynthetic Carbon Assimilation, doctor of biological sciences H.G.Babayev has been published. The book summarizes extensive original materials and literature on the study of the biochemical adaptation of plants to the effects of drought and other abiotic stressors. The authors mainly focused on the enzymes involved in the carbon and nitrogen metabolism in tissues and subcellular fractions of higher plants differing in photosynthetic mechanisms, their subcellular localization, isoenzyme spectra, effects of inhibitors and regulation of these enzymes by some metabolites and changes in physicochemical and kinetic properties under stress. Changing of enzymes and activity of proton pumps in the roots were comparatively analyzed. The book is intended for researchers working in biochemistry, plant physiology, enzymology, and photosynthesis. The book can also be used by high school students who study relevant specialties and teachers.