The International Union of Speleology (Union Internationale de Spéléologie, UIS) is a non-profit, non-governmental organization founded in 1965 in Slovenia (part of former Yugoslavia) on the initiative of the 4th International Congress of Speleology. Since 1953, these congresses are held every four years to promote interaction between academic and technical speleologists of different nationalities and with the purpose of developing and coordinating international speleology in all of its scientific, technical, cultural and economic aspects. The Union consists of member nations with voting rights, and each is represented by a delegate who represents all cavers and speleologists in its country. Until this book, the history of the International Union of Speleology was spread out in the minutes of the meetings and general assemblies, various UIS publications, and the proceedings of its International Congresses. Moreover, much of it was never written and was available only from the memories of past presidents, secretaries and other members of the UIS. In this book, the author presents the purpose of the Union and summarizes all its events through the first 50 years of its existence. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Mednarodna speleološka zveza (Union Internationale de Spéléologie, UIS) je neprofitna, nevladna organizacija, ustanovljena leta 1965 v Sloveniji (v nekdanji Jugoslaviji), na pobudo 4. Mednarodnega speleološkega kongresa. Kongresi so organizirajo na vsake štiri leta že od leta 1949, z namenom spodbujanja sodelovanja med akademskimi in tehničnimi jamarji različnih narodnosti ter z namenom razvijanja in usklajevanju mednarodnega jamarstva iz znanstvenih, tehničnih, kulturnih in ekonomskih vidikov. Zvezo sestavljajo člani z volilno pravico, vsako državo pa zastopajo delegati, ki predstavljajo vse jamarje in speleologe v državi. Do te knjige je bila zgodovina Mednarodne speleološke zveze zapisana samo v zapisnikih sestankov, generalnih skupščin in različnih publikacijah ter zbornikih njenih mednarodnih kongresov. Veliko pa sploh ne, bilo je samo v spominih preteklih predsednikov, tajnikov in drugih upravnih članov UIS-a. V tej knjigi avtor povzema vse dogodke in namen zveze skozi 50 let njenega obstoja.