This review covers the isolation, structure determination, synthesis, chemical transformations and biological activity of indolizidine and quinolizidine alkaloids from microbial, plant and animal sources. Included in the review are slaframine; the hydroxylated indolizidines lentiginosine, swainsonine, castanospermine and their analogues; alkaloids from amphibians and marine sources; plumerinine; ipalbidine, phenanthroindolizidines and related alkaloids; lasubine-II: and lupin alkaloids. The literature from July 2001 to June 2002 is reviewed, and 142 references are cited.