The use of chlorine for purification of water in swimming pools is well-established for both private and commercial purposes. Although salt-water chlorination has found sane use in private pools, most of these pools and the larger public pools with high chlorine demands and needs for unequivocal control of water quality, still use hypochlorite or chlorine gas. It is common to blame eye irritation upon “too much chlorine” in pools, yet there is no conclusive work to verify that pool chlorine is directly responsible for the problem. Indeed, the snail amount of work done so far has mainly looked at chloro-nitrogen compounds as the source of irritation. Little regard has been given to the roles that pool osmolarity and pH might play, or to whether the problem could be associated with the presence of other chloro-compounds such as trihalanethanes. A review is given of the results of previous work on the problem, and details described of experiments, recently comenced, which aim to identify the factors underlying eye reactions to swimming pool water.