Oscar Pistorius held his head in his hands and retched as he waited to speak for the first time at his trial for killing Reeva Steenkamp.

The fallen track star was passed a bucket during the first morning back in court, following a week-long adjournment.

Pistorius has vomited on several occasions during proceedings at North Gauteng High Court since the trial started a month ago.

His voice wavered and nearly broke while he was being sworn in on the witness stand.

This morning (Monday) there was shock in the courtroom when a gruesome image was shown of Steenkamp's head after it was blasted by Pistorius.

The 29-year-old Steenkamp died after Pistorius shot her four times through the bathroom door of his luxury apartment. The killer shot hit Steenkamp in the head, while she was also injured in the hip and arm.

Pistorius also got a front-row seat to see prosecutor Gerrie Nel go on the attack against pathologist Jan Botha.

Pistorius denies murder and claims he mistook Steenkamp for an intruder at his luxury home. However the prosecution alleges he killed her following an argument.

The trial continues.