WARNING: This story discusses incidents of sexual assault which some readers may find distressing.

A Perth dentist who spiked the drinks of women he met on dating apps and then sexually assaulted them, has been sentenced to 15 years in jail.

Farzam Mehrabi, 34, always denied the allegations against him but after a four-week trial in the District Court he was found guilty of more than 20 offences, including sexual penetration without consent, stupefying another and impeding the breathing of a person.

The court was told that over a two month period in 2022, Mehrabi met the women, aged between 18 and 22, on dating apps where he lied about his age, before arranging to meet them.

The prosecution said he then put drugs, including MDMA and methamphetamine, into drinks he either bought, or made for them, before having non-consensual sex with them.

A total of five women were drugged but one of them, the final victim, was not sexually assaulted.

A sixth woman was sexually assaulted, but the jury found Mehrabi not guilty of spiking her drink.

The evidence against Mehrabi included CCTV footage from a bar, which showed him putting something into the drink of one of the victims after she went to the bathroom.

Another victim testified she remembered drinking with him before she started to feel unwell and vomited.

Her next memory was waking up in his bedroom and finding injuries on her body.

Mehrabi, who was studying to become a facial surgeon, denied any wrongdoing, but the jury rejected his testimony and found him guilty of 21 charges.

At the start of his trial Mehrabi also admitted to three charges of offering to supply a prohibited drug to another.

During her sentencing remarks, Judge Troy Sweeney described the CCTV footage from the bar as "damming", saying Mehrabi was so "emboldened" at that point that he was willing to spike the woman's drink in full view of security cameras.

The court was told when the woman in that footage became unwell she managed to get out of Mehrabi's vehicle and railway officers at a nearby train station called the police.

It was her complaint, and a subsequent police appeal for information, that led to Mehrabi's crimes against the other five women being investigated.

The court heard while some of the women had voluntarily taken MDMA with Mehrabi, others had made it clear to him that they did not want to use drugs and so he had spiked their drinks without their knowledge.

Judge Sweeney described Mehrabi as having "a sense of entitlement".

"As a good looking, educated, up-and-coming dentist, soon to be surgeon, you believed you were entitled to live this way," Judge Sweeney told him.

Judge Sweeney said it was "extraordinary" that a man of his educational background would facilitate the taking of an illegal drug, describing his actions is as "immature" and "negligent".

She sentenced him to 15 years in prison, and he will have to serve 13 before being considered for parole.