Orchids are one of the largest plant families and are commercially traded for a variety of purposes, including as ornamental plants, medicinal products and food. These markets involve thousands of species, which may be traded legally or illegally, sustainably or unsustainably, and take place at local, national or international scales. In this review, we provide the first overview of commercial orchid trade globally and highlight the main types that involve wild-collected plants. Much of this trade is the result of illegal harvest meaning that it is little documented and is absent from official statistics, at the same time as being of growing conservation concern. We discuss the associated legal-regulatory context, identify key conservation challenges and highlight four key priorities for addressing these challenges. These are to (1) research trade dynamics and the impacts of harvest; (2) strengthen the legal trade of orchids; (3) adopt measures to reduce illegal trade, and (4) raise the profile of orchid trade among policy makers, conservationists and the public.