Sources, sinks, and distribution patterns ofvolatile halogenated organic compounds (VHOC)in estuaries were investigated during 5 cruises within the BIOGEST programme. Due to their chemical and physical properties (e.g. toxicity, persistence, mobility) these compounds are of considerable environmental concern. A wide range of compounds has been identified and quantified generally ranging from 0.1 ng l−1 to 350 ng l−1. Insome samples extraordinarily high values up to4700 ng l−1 were observed indicatingcontribution from anthropogenic sources.Generally, concentrations of halogenatedcompounds of anthropogenic origin dominatedthose of prevalent natural origin. Data ofselected VHOC are presented in relation tosalinity, particular organic carbon, and totalsuspended matter. Furthermore the observedconcentrations are compared with establishedwater quality regulations. Distributionpatterns of VHOC along the estuary indicatedcommon sources for specific halogenatedcompounds. Decreasing concentrations of mostVHOC along the estuary confirm that degassingto the atmosphere and dilution with sea waterare the dominating processes controlling thefate of these compounds in estuaries.