V.V. Burdyuzha Astro Space Centre, Lebedev Physical Institute, Russian Academy of Sciences, ul. Profsoyuznaya 84/32, Moscow, 117997, Russian Federation
CONTENTS 1. Introduction 763 2. Masers in the local galaxy 763 3. Summary of the characteristics of galaxies with OH-molecule megamasers 764 4. Production of OH molecules, their abundance, and spectroscopic features of low-lying rotational levels 765 5. Possible mechanisms for the formation of a population inversion in OH megamasers; energy estimates 766 6. H2O and H2CO megamasers 768 7. Conclusion 769 References 770