Well-written curriculum materials are known to support teacher learning. Less discussion has focused on whether teachers' guides, curriculum materials written specifically for teachers by textbook publishers, provide sufficient support. In this study, I analyse four US-based mathematics teachers' guides to understand the opportunities within them for teacher learning. Drawing on positioning theory, I conceptualised teacher learning opportunities as teacher positionings observable from teachers' guides. With this conceptualisation, I explored teacher positionings that were regularly or idiosyncratically observable from the selected teachers' guides. The results revealed only a small number of regularly observable positionings existed, indicating limited opportunities for teacher learning from the guides. Irregularly, or idiosyncratically observed positionings provided limited opportunities, as well. Based on the findings, I suggest the necessity of presenting diverse positionings to best utilise the potential from teachers' guides as materials for teacher learning.