A perusal of the letterature relating to the estuarine fauna reveals that very little attention has been paid to the study of chaetognaths. A review of the earlier work done on chaetognaths from various estuaries of India is given here. In addition, this account deals with the seasonal fluctuations and abundance of three species of Sagitta  namely, S.bedoti Beraneck,  S.inflata Grassi and S. pulchra  Doncaster, occuring in the estuarine areas around Cochin. Material of different maturity stages of S. inflata  from the estuarine and marine enviornments are also compared.