The liver X receptors (LXRα and LXRβ) are members of the nuclear receptor family of transcription factors. The activation of LXR induces genes involved in reverse cholesterol transport (RCT), which is believed to be the main effect of LXR agonists in the prevention or treatment of atherosclerosis. However LXR agonists have also been shown to cause hepatic steatosis and hypertriglyceridaemia. The ability to separate beneficial effects from negative effects has been a challenge that so far has hampered the development of LXR agonists for human use. We herein describe the SAR and optimization of a series of trioxoisothiazole-based LXR agonists leading to compounds with nanomolar potencies and a separation of beneficial versus negative effects in vivo. This work ultimately led to the nomination of AZD3971 as a candidate for the treatment of atherosclerosis.