A motorcyclist has died following a collision on the A4069 near Brynamman, Dyfed-Powys Police have said.
The crash happened at around 1.10pm on Sunday on the stretch of road between Brynamman and the Black Mountain.
Officers said it involved a silver Triumph motorcycle and a red Honda motorcycle.
The rider of the silver Triumph, a 48-year-old man, died at the scene, the force said.
Police said his next of kin have been informed and are being supported by specialist officers.
The rider of the red Honda, a 42-year-old woman, suffered serious injuries and was taken to hospital, where she remains.
Officers said her next of kin have also been notified.
The road was closed while collision investigators carried out their work, and reopened at around 8pm.
The A4069 over the Black Mountain is a well-known route, popular with motorcyclists and drivers for its sweeping climbs and views over the Tywi Valley.
Dyfed-Powys Police are appealing for anyone who was travelling along the A4069 at the time to come forward.
Officers said they are particularly keen to hear from any motorists in the area who have dashcam footage.
Anyone with information is asked to contact Dyfed-Powys Police.
