This study provides a comprehensive analysis of the secretome of seven different Leishmania species (six main human pathogenic species: L. donovani, L. infantum, L. braziliensis, L. major, L. amazonensis, L. tropica) and L. tarentolae, non-pathogenic to humans, produced by promastigotes cultured in serum-free conditions. The exhaustive analysis of the protein content of the secretome using mass spectrometry led to the identification of common and unique proteins, as well as useful insights on the relation between secretome content and pathogenesis. The biological relevance of the secretome is undeniable and, in the particular case of Leishmania parasites, it is a crucial player in the host-pathogen interactions which dictate the outcome of infection and disease severity. This study actively contributes to current knowledge on Leishmania biology and the generated datasets are an addition to current databases, associating the identified proteins with subcellular localization and putative extracellular functions.