In this study, the simultaneous presence of eight polybrominated diphenyl ethers (PBDEs), nine new brominated flame retardants (NBFRs) and ten organophosphorus flame retardants (OPFRs) was investigated in dust samples collected from different indoor environments (homes, schools, theatres, a university and a Research Institute) in Barcelona, Spain. OPFRs were detected at the highest concentrations followed by PBDEs. ∑OPFRs ranged from 2053 to 72,090 ng g-1 and tris(2-chloroisopropyl) phosphate (TCIPP) was the most abundant compound. BDE-209 was the main PBDE congener detected (up to 14,990 ng g-1), while other PBDEs ranged from 2.6 to 118 ng g-1. Among the studied NBFRs, decabromodiphenyl ethane (DBDPE - up to 4432 ng g-1) followed by bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP - up to 508 ng g-1) were detected at the highest concentration, whereas a lower detection frequency was observed for 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), pentabromotoluene (PBT) and hexabromobenzene (HBB). The levels and profile of flame retardants (FRs) were characteristic of each environment, where theatres followed by homes presented the highest concentrations and schools had the lowest levels. Principal Component Analysis permitted to identify the main sources and distribution of all FRs, according to specific uses in each environment. The simultaneous presence of all FR families in indoor dust points to the need to monitor these compounds to minimize human exposure.