Several steroidal esters of alkylating agents have been synthesized and tested in vitro and in vivo in various experimental cancer types. 3 beta-Hydroxy-17 alpha-aza-D-homo-5-androsten-7,17-dione-N,N-bis(2-chloroethy1) aminophenylacetate (1) is a highly active compound. DSC scans show differences between the alkylating agent alone and in conjugation with the steroidal part in the broadening and lowering of the phase transition of DPPC bilayers. These differences may in part explain the better pharmacokinetic profile and lower toxicity of conjugated congener I versus the alkylating agent alone. (c) 2004 Elsevier B.V. All rights reserved.