ERPLAB is an open-source toolbox for processing and analyzing event-related potential (ERP) data in the MATLAB environment. It is closely integrated with EEGLAB, a popular open-source toolbox for EEG preprocessing, and provides additional tools for filtering, artifact detection, re-referencing, and event sorting. ERPLAB offers robust tools for averaging EEG segments, creating difference waves, filtering and re-referencing averaged ERPs, plotting ERP waveforms and scalp maps, and quantifying amplitudes and latencies. The toolbox can be accessed through a user-friendly graphical interface or via MATLAB scripts, making it accessible to both novice and experienced researchers. ERPLAB supports various data acquisition systems and is compatible with major computer operating systems. It includes detailed documentation, including a user's guide, tutorials, and video demonstrations, and provides support via email and a general email list. The toolbox aims to provide a comprehensive and flexible solution for ERP analysis, addressing the limitations of commercial packages and offering advanced features for state-of-the-art research.ERPLAB is an open-source toolbox for processing and analyzing event-related potential (ERP) data in the MATLAB environment. It is closely integrated with EEGLAB, a popular open-source toolbox for EEG preprocessing, and provides additional tools for filtering, artifact detection, re-referencing, and event sorting. ERPLAB offers robust tools for averaging EEG segments, creating difference waves, filtering and re-referencing averaged ERPs, plotting ERP waveforms and scalp maps, and quantifying amplitudes and latencies. The toolbox can be accessed through a user-friendly graphical interface or via MATLAB scripts, making it accessible to both novice and experienced researchers. ERPLAB supports various data acquisition systems and is compatible with major computer operating systems. It includes detailed documentation, including a user's guide, tutorials, and video demonstrations, and provides support via email and a general email list. The toolbox aims to provide a comprehensive and flexible solution for ERP analysis, addressing the limitations of commercial packages and offering advanced features for state-of-the-art research.