Prior to our recent publication (J. Akerman et al, IEEE Trans. Dev. Mat. Rel. 4, p.428-435, 2004), little data on magnetoresistive random access memory (MRAM) reliability were available in the literature. In this paper, we present additional reliability data taken in full 4 Mb MRAM arrays, significantly extending the scope of our original study. In particular, we present good reliability over 10 years against dielectric breakdown, resistance drift, drift of programming currents, electromigration, and also demonstrate solid data retention. This study further solidifies our expectations of MRAM becoming the memory technology of choice for high-performance non-volatile memory applications where endurance and reliability are crucial requirements.