ABSTRACT Sterols are very well known for their important roles in membranes and signaling in eukaryotes. Plants stand out among eukaryotes by the large variety of sterols that they can produce, and employing them across a wide spectrum of physiological processes. Therefore, it is critical to understand the wiring of the biosynthetic pathways by which plants generate these distinct sterols, to allow manipulating them and dissect their precise physiological roles. Many enzymatic steps show a deep evolutionary conservation, while others are executed by completely different enzymes. Here, we review the complexity and variation of the biosynthetic routes of the most abundant phytosterols in the green lineage and how different enzymes in these pathways are conserved and diverged from humans,yeast and even bacteria. Based on their evolutionary conservation we discuss the use of human and yeast sterol biosynthesis inhibitors in plants, as an argument for the development of plant-tailored inhibitors of sterol biosynthesis.