Some generalizations of Bailey's theorem involving the product of two Kummer functions 1 F 1 are obtained by using Watson's theorem and Srivastava's identities. Its special cases yield various new transformations and reduction formulae involving Pathan's quadruple hypergeometric functions F p ( 4 ) , Srivastava's triple and quadruple hypergeometric functions F ( 3 ) , F ( 4 ) , Lauricella's quadruple hypergeometric function F A ( 4 ) , Exton's multiple hypergeometric functions X E : G ; H A : B ; D , K 10 , K 13 , X 8 , ( k ) H 2 ( n ) , ( k ) H 4 ( n ) , Erdélyi's multiple hypergeometric function H n , k , Khan and Pathan's triple hypergeometric function H 4 ( P ) , Kampé de Fériet's double hypergeometric function F E : G ; H A : B ; D , Appell's double hypergeometric function of the second kind F 2 , and the Srivastava-Daoust function F D : E ( 1 ) ; E ( 2 ) ; … ; E ( n ) A : B ( 1 ) ; B ( 2 ) ; … ; B ( n ) . Some known results of Buschman, Srivastava, and Bailey are obtained.