An experimental and numerical investigation of the effect of bisphenol A bis(diphenyl phosphate) (BDP) and polytetraﬂuoroethylene (PTFE) on the ﬁre behaviour of bisphenol A polycarbonate/acrylonitrile butadiene styrene (PC/ABS) in the vertical UL 94 scenario is presented. Four PC/ABS blends were discussed, which satisfy different UL 94 classiﬁ cations d ue to the competing ef fects of gasiﬁca ti on, charring, ﬂame inhibition and melt ﬂow/dripping. For numerical investigation, the particle ﬁnite element method (PFEM) is used. Its capability to model the complex ﬁre behaviour of polymers in the UL 94 is analysed. The materials’ properties are characterised, in particular the additives impact on the dripping behaviour during thermal exposure. BDP is an efﬁcie nt p lasticiser; adding PTFE p reve nts dripping by causing a ﬂo w limit. P FEM simulation s reproduce the dripping and burning behaviour, in particular the competition between gasiﬁcation and dripping. The thermal impact of both the burner and the ﬂame is approximated taking into account ﬂame inhibition, charring and effective heat of combustion. PFEM is a promising numerical tool for the investigation of the ﬁre behaviour of polymers, particularly when large deformations are involved. Not only the principal phenomena but also the different UL 94 classi ﬁ cations and t he exti nc tion times are well predicted.