The sensitivity of N-terminal sequencing has been used to identify proteins expressed by the newly excysted juvenile stage of the parasite Fasciola hepatica. Of the seven proteins identified, a number have significant sequence homology to the cysteine proteases: cathepsin B, cathepsin L and asparaginyl endoproteinase. Proteolytic activity was demonstrated using gelatin substrate sodium dodecyl sulphate polyacrylamide gel electrophoresis. In addition, a number of novel proteins were identified which shared no significant sequence homology to proteins in the databases. The availability of such N-terminal sequence information allows rapid identification of major proteins from scarce developmental stages and provides the basis for further molecular studies.