Previous studies have shown that magnetic resonance imaging is a very appropriate non-invasive technique for quantifying the growth of somatic and gonadic tissues and sex determination in the Pacific oyster, Crassostrea gigas. Despite a thinner gonad, harder to distinguish than that of the Pacific oyster, we showed in this study that it was possible to distinguish and quantify the development of the gonad of the European flat oyster, Ostrea edulis, using a 3D MRI sequence with a suitable finer resolution. Compared to T2-weighted images, theoretically the most appropriate for good anatomical description, T1-weighted images were more suited to gonad observation. The gonad development was quantified by the number of voxels with higher grey level. Larvae were then depicted in the intervalvar cavity of spawning females. MRI imaging is a non-invasive method that is well suited to the description of gametogenesis in the European flat oyster. (C) 2010 Published by Elsevier B.V.