The stellar mass and metallicity are among the fundamental parameters of galaxies. An understanding of the interplay between those properties as well as their environmental dependence will give us a general picture of the physics and feedback processes ongoing in groups of galaxies. We study the relationships and environmental dependencies between the stellar mass, and gas metallicity for more than 1900 galaxies in groups up to redshift 0.35 using the Galaxy And Mass Assembly (GAMA) survey. Using a control sample of more than 28000 star-forming field galaxies, we find evidence for a decrement of the gas metallicity for galaxies in groups. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.