Radium isotopes are widely used in marine studies (eg. to trace water masses, to quantify mixing processes or to study submarine groundwater discharge). While Ra-228 and Ra-228 are usually measured using gamma spectrometry, short-lived Ra isotopes (Ra-224 and Ra-223) are usually measured using a Radium Delayed Coincidence Counter (RaDeCC). Here we show that the four radium isotopes can be Ra-228 Ra-224 223 analyzed using gamma spectrometry. We report Ra-226 Ra activities measured using low-background gamma spectrometry in standard samples, in water samples collected in the vicinity of our laboratory (La Palme and Vaccares lagoons, France) but also in seawater samples collected in the plume of the Amazon river, off French Guyana (AMANDES project). The Ra-223 and Ra-224 activities determined in these samples using gamma spectrometry were compared to the activities determined using RaDeCC. Activities determined using the two techniques are in good agreement. Uncertainties associated with the Ra-224 activities are similar for the two techniques. RaDeCC is more sensitive for the detection of low Ra-223 activities. Gamma spectrometry thus constitutes an alternate method for the determination of short-lived Ra isotopes. (C) 2009 Elsevier Ltd. All rights reserved.