Soil microbial community structure and activity are linked to plantcommunities. Weeds may alter their soil environment, selecting for specificrhizosphere microbial communities. Rhizosphere modification occurs for manycrop and horticultural plants. However, impacts of weeds in agroecosystemson soil biology and ecology have received less attention because effectiveweed management practices were developed to minimize their impacts on cropproduction. The recent development of herbicide resistance (HR) in severaleconomically important weeds leading to widespread infestations in cropfields treated with a single herbicide has prompted a re-evaluation of theeffects of weed growth on soil biology and ecology. The objective of thisarticle is to review the potential impacts of herbicide-resistant weeds onsoil biological and ecological properties based on reports for crops, weeds,and invasive plants. Persistent weed infestations likely establish extensiveroot systems and release various plant metabolites through root exudation.Many exudates are selective for specific soil microbial groups mediatingbiochemical and nutrient acquisition processes. Exudates may stimulatedevelopment of microbial groups beneficial to weed but detrimental to cropgrowth or beneficial to both. Changes in symbiotic and associative microbialinteractions occur, especially for arbuscular mycorrhizal fungi (AMF) thatare important in plant uptake of nutrients and water, and protecting fromphytopathogens. Mechanisms used by weeds to disrupt symbioses in crops arenot clearly described. Many herbicide-resistant weeds including Amaranthus and Chenopodium do notsupport AMF symbioses, potentially reducing AMF propagule density andestablishment with crop plants. Herbicides applied to control HR weeds maycompound effects of weeds on soil microorganisms. Systemic herbicidesreleased through weed roots may select microbial groups that mediatedetrimental processes such as nutrient immobilization or serve asopportunistic pathogens. Understanding complex interactions of weeds withsoil microorganisms under extensive infestations is important in developingeffective management of herbicide-resistant weeds.