Fifty-seven Roman Glass fragments coming from Braga (Portugal) were analyzed by inductively coupled plasma-mass spectrometry, determining a total of 63 major, minor and trace elements including rare earth elements. Different faults were described in the glass samples such as mass irregularities, surface physical alterations and presence of biological material. Samples were classified in three groups according to their major elements. Several statistical analyses were applied to chemical composition. Supervised pattern recognition was used to group glasses based on their colour and date. Undated samples were classified into previously established dated glass groups.