According to local reports, the 30-year-old was taken from Atteridgeville Prison to Kalafong Hospital in Pretoria at 8am this morning having complained of severe chest pains.
Logan Maistry, a spokesperson for South Africa's Department of Correctional Services, told ABC News that Pistorius was taken to a medical facility for a checkup but declined to provide further details.
Pistorius was moved from the Kgosi Mampuru II Prison to the Atteridgeville Correctional Centre past year because it had better facilities to suit his needs.
Britain's Prince Philip ends 65 years of official engagements
It comes after he announced he would retire in the autumn after completing 22,219 solo engagements since 1952. The BBC reported that the rank will pass to Philip's grandson Prince Harry following his retirement.
The year before he killed Steenkamp, Pistorius became the first double-amputee to race at Olympic level when he appeared at the London 2012 games.
Neither prison authorities nor Pistorius' family have confirmed the cause of his chest pains.
His trial became the subject of widespread worldwide attention, as he was initially cleared of murder in favour of a manslaughter charge - then convicted of murder on appeal in 2016. A year ago he received treatments after he sustained cuts to his wrists, which he said were the result of a fall in his cell.
Tactics, events that defined Joe Arpaio's career as sheriff
Arpaio later faced a civil trial for ignoring several orders, and he was found guilty of civil contempt of court a year ago . But Arpaio, Bolton concluded, came up with what he described as his backup plan: turn illegal immigrants over to the U.S.
The Telegraph reported that initially, the media made claims that Pistorius' injury was "self inflicted" and that he had tried to commit suicide inside his cell.
Early reports suggest staff at the Atteridgeville Prison believed he had suffered a heart attack. Please let us know in the comments.
HTC Teases Standalone Vive VR Headset for China
And for another, they're both utilizing the Snapdragon 835 processor for power that doesn't have to come from a desktop or laptop. HTC has revealed that it plans to release a standalone Vive VR headset in the Chinese market at some point in the near future.