Abstract: The present invention provides a drug-dendrimer conjugate comprising a central core, two or more linear hydrophilic molecules bonded thereto, a secondary core molecule bonded to at least a majority, if not all, of said first linear hydrophilic molecules, a drug or other biologically-active molecule bonded to the remainder of said first linear hydrophilic molecules or bonded to a segment comprising a second secondary core molecule which is bonded to said first secondary core molecule by a linear hydrophilic molecule, and wherein at least some of the bonds between said drug or other biologically active molecule and said first and/or second secondary core molecules are hydrolysable by an endogenous esterase.