A single maturity classification key applied to five common chaetognath spe
cies of the eastern Mediterranean is presented. The efficiency of the key w
as tested using biometrical data: body length (BL), ovary length (OL) and s
eminal vesicle width (SVW). For each species the key proved easy to use and
efficient in the distinction of the maturity stages providing a satisfacto
ry size separation between them.