A data release containing information on macroinvertebrate communities and sediment toxicity in the Buffalo River Area of Concern (AOC) and reference areas immediately upstream of the AOC collected during 2017 and 2020. Macroinvertebrate community samples were collected using bottom-deployed multiplate artificial substrate samplers and organisms were identified to the lowest practical taxonomic resolution and used to calculate metrics of biological integrity following standard New York State Department of Environmental Conservation procedures. Bed sediments were collected using a petite Ponar dredge and used for toxicity tests with two test species, Chironomus dilutus and Hyalella azteca, following USEPA test methods 100.2 and 100.1, respectively. In situ habitat measurements and sediment samples for determination of grain size distribution and total organic carbon concentration were also taken at the time of sample collection at all sites. The data release has four separate tables: one containing site locations and habitat information, one containing the results of 10-day sediment toxicity tests, one containing macroinvertebrate identifications, and one containing standard New York State Department of Environmental Conservation metrics of macroinvertebrate community integrity calculated from the macroinvertebrate identifications. First posted – May 10, 2019 (version 1.0, available from author) Revised – September 17, 2021 (version 2.0) Version 1.0: This version of the dataset contains one table that contains the results of sediment toxicity tests from 2017. All data in Version 1.0 are contained in Version 2.0. Version 2.0: This version of the dataset has four separate tables with data from 2017 and 2020 sampling events: one containing site locations and habitat information, one containing the results of 10-day sediment toxicity tests, one containing macroinvertebrate identifications, and one containing standard New York State Department of Environmental Conservation metrics of macroinvertebrate community integrity calculated from the macroinvertebrate identifications. Additionally, the title of the data release has been changed from "Data for Assessing the Status of Macroinvertebrate Communities and Sediment Toxicity in the Buffalo River Area of Concern, New York" to "Macroinvertebrate community and sediment toxicity data from the Buffalo River Area of Concern, New York (ver. 2.0)". All data in Version 1.0 have been retained in Version 2.0 and are unchanged.