Market sociology research has accounted amply for the importance of material devices in shaping markets. In contrast, the influence of biological entities (such as parasites, soil, and food) on market agencing has barely been considered. This article shows the relevance of covering this matter specifically. To do so, the authors refer to their analyses of the production and sales practices of organic vegetable market actors in France. Based on descriptions of four situations, they show that the biological processes involved in the cultivated ecosystems and agricultural produce itself influence the market agencing processes that these actors carry out. Based on these first observations, they propose four generic statements that clarify what considering the action of biological entities involves in terms of theory and identify avenues for future research.