Chloride (Cl-) has often been assumed to be relatively unreactive in forest ecosystems, and is frequently used as a conservative tracer to calculate fluxes of water and other ions. Recently, however,several studies have detailed cycling of Cl- invegetation and soils. In this study Cl- budgets arecompiled from 32 catchment studies to determine the extent to which Cl- is conserved in the passage through forest ecosystems. Chloride budgets fromthese sites vary from net retention (input/output) tonet release (output/input). In the overall data set, including those sites with very high inputs of seasaltCl-, there was a strong correspondence betweeninputs and outputs. However, sites with low Cl- deposition (<6 kg ha-1 year-1) consistently showednet release of Cl-, suggesting an internal source or adeclining internal pool. The results indicate that Cl- may be a conservative ion in sites with high Cl- deposition, but in sites with low deposition Cl- may not be conservative. We discuss the possible causes of the Cl- imbalance and reasons why Cl- may not be conservative in ecosystem functions.