Leishmaniasis is among the most important infectious diseases of the develo
ping world. With the advent of effective culture conditions for the various
stages of the life cycle, together with state of the art biochemical, geno
mics, and reverse genetic approaches, it has been possible to identify viru
lence factors required for the infection process. Several of these virulenc
e factors are discussed within including lipophosphoglygan, A2, cysteine pr
oteinases, and gp63.