Laser lithotripter is by far the most commonly used intracorporeal lithotriper. Despite the recent exciting in-roads made by the thulium fibre laser (TFL), currently, the holmium: yttrium-aluminium-garnet (Ho:YAG) laser is the lithotripter of choice for the treatment of urinary stones. This article aims to provide a concise review of the Ho:YAG laser used with flexible ureteroscopy for the treatment of renal stones. The review examines the technical aspects, the laser fibre, the setting and efficiency of Ho:YAG laser. This is a narrative review of the Ho:YAG laser used with flexible ureteroscopy in the treatment of renal stones. The relevant databases and journals in urology were searched for contemporary existing literature on the subject. The literature on the physics, the anatomy of the Ho:YAG fibre, the setting and efficiency of the Ho: YAG laser were reviewed. The safety of the Ho:YAG laser in the treatment of renal stones was also reviewed. Understanding the physics of Ho:YAG laser, proper choice of laser fibres and appropriate setting of the laser machine are essential for its optimal use in flexible ureteroscopy for renal stone.