Botanical residues recovered from excavations in the Southeast Marketplace of Piedras Negras provide information about the healing and medical activities of the site's Classic period (a.d. 350-900) inhabitants, and point towards the intersection between commerce and medicine for the ancient Maya. The plants were likely exchanged at the market then used on-site for the purposes of healing. The botanical remains are complemented by both architectural and bioarchaeological evidence for healing at this locus, including a high concentration of sweatbaths and evidence for palliative tooth extraction. With the aid of ethnohistory, we identify health care practices potentially associated with the plant remains. However, we expand on basic understandings of "healing" with a critical look at how some medicinal plants may have been ritually invoked, even when never directly ingested or applied topically.