Although landfills represent repositories for cumulative loading of plastic waste derived from households and industrial sectors, often seen as sinks, the contribution of these structures and their leachates as potential sources of microplastics to natural environments remains poorly covered. Microplastics discharged from these sites may pose greater risks to human and environmental health by adsorbed highly toxic and persistent hazardous chemicals. As reviewed here, landfill leachates present microplastic concentrations of 0 – 291 particles L-1, highly variable depending on landfill conditions and methodologies adopted, while treatment of leachates can reduce these concentrations in 1 to 2 orders of magnitude. Nonetheless, knowledge is still scarce on the factors influencing the release of microplastics from landfills and technology must be developed to mitigate this source of microplastics, which poses a significant challenge but is needed in order to preserve a good environmental status. Thanks are due to CESAM (UIDP/50017/2020 ​+ ​UIDB/50017/2020), with the financial support from FCT/MCTES through national funds. To the research project comPET (PTDC/CTA-AMB/30361/2017), funded by FEDER, through COMPETE 2020 - Programa Operacional Competitividade e Internacionalização (POCI), and by national funds (OE), through FCT/MCTES. J.C.P. and A.L.P.S. were funded by Portuguese Science Foundation (FCT) through PD/BD/135581/2018 scholarship and CEECIND/01366/2018 research contract, respectively; under POCH funds, co-financed by the European Social Fund and Portuguese National Funds from MEC. Peer reviewed