The temporal variations of spring water chemistry are used to support observations on the nature of groundwater circulation inside a karstified carbonate terrain. Variations in some hydrochemical properties such as the Ca++/Mg++ratio, the hardness, the electric conductivity, the CO2partial pressure, and the calcite and dolomite saturation ratios are used to give indications with regard to the nature of the carbonate rock, the groundwater residence time, and the mode of water circulation inside the karstic system. The seasonal variations of these properties during four years of monitoring were determined for six adjacent springs in a karstified carbonate terrain in northwest Iraq. The carbonate terrain, which is known to be mostly limestone with some dolomitic limestone beds, has given an average value of 3.3 for the Ca++/Mg++ratio. The magnesium and calcium hardness has high values (341–368 ppm) with a coefficient of variation that exceeds 11%. The PCO2has a minimum of 10−2.7bar and a maximum of 10−1.8bar. The values of the calcite and dolomite saturation indices fluctuate about saturation levels in spite of the presence of an appreciable concentration of NaCl. These results, when combined with other analyses and observations related to the flow rate characteristics of the springs, have revealed that the six springs are fed by a common diffuse type karstic system with a rather high but acceptable coefficient of variation of hardness.