Al-Sulaibiya field is the oldest and the largest groundwater well field producing brackish groundwater from the Dammam Formation aquifer. Total dissolved solids (TDS) values of the Dammam Formation aquifer of Al-Sulaibiya field are very high, they are in the range of 3523-9460 mg/l. Therefore, the interrelationships between the TDS, electrical conductivity (EC), sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl-), sulfate (SO42-), and bicarbonate (HCO3-) were examined to trace out the groundwater quality trends of the Dammam Formation aquifer of Al-Sulaibiya field. Kuwait during the period 1991-2005. The variable most strongly correlated with TDS was electrical conductivity (EC). (C) 2009 Elsevier B.V. All rights reserved.