The New York-based rights group accused President Bashar al-Assad's forces of systematically targeting hospitals and medical personnel on an unprecedented scale in modern warfare, and said this amounted to crimes against humanity.
Over the past four years, a total of 610 medical personnel were killed, 139 of whom were tortured or executed, according to the report released at UN headquarters.
Assad's forces are responsible for 97 percent of the killings, it said.
The report also documented 233 attacks on 183 hospitals and clinics, most recently with the use of deadly barrel bombs.
"The Syrian government has resorted to every tactic: emergency-room arrests, hospital bombings -- including barrel bombs -- and even the torture and execution of doctors who attempt to treat the wounded and sick," said Erin Gallagher, director of investigations for Physicians for Human Rights (PHR).
Attacks on medical workers are a violation of international humanitarian law, but the rights group noted that "when the attacks are as widespread and systematic as they are in Syria, they constitute crimes against humanity."
Widney Brown, PHR's director of programs, said the group has received reports of "hundreds" of doctors held in detention or who have simply disappeared, but PHR was not able to verify those accounts.
The release of the report -- partly compiled from data from PHR's "field sources" inside Syria -- came as the war enters its fifth year with little prospect for peace.
- Targeted at hospital -
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Attacks on medical staff and hospitals have devastated the medical infrastructure, with some 15,000 doctors, or well over half of all medics, forced to flee the country since the conflict began in 2011.
"The scale and the scope of the assault on health and health workers conducted by the Syrian government is unprecedented," said Susannah Sirkin, the group's director of international policy.
The report said the Syrian government was responsible for 88 percent of all hospital attacks.
Syrian doctor Majed Abu Ali, from Eastern Ghouta, said only 10 doctors remained in the besieged region out of 100 four years ago, including an orthopedic surgeon who suffered burns to his face and arms when a rocket hit his hospital last month.
The doctor, who used a fake name out of fear for his family's safety, said he had been arrested twice and faced problems when trying to renew his passport after he set up a field hospital.
"If you are a doctor in Syria, it means you will spend every moment of your life trying to save others' lives, but your own life will be threatened and you can be targeted at any moment in your own hospital," he said.
According to the report, 287 medics were killed during shelling or bombing of their hospitals, and 165 were shot dead, mostly by sniper fire.
The rights group accused the UN Security Council of "utterly" failing in its duties to uphold international law and pointed the finger at Russia and China for blocking a resolution referring Syria to the war crimes court.
"These crimes rightly belong before the International Criminal Court," said Sirkin.
The group called on the Security Council to ensure those responsible for attacks on medical personnel are held accountable, and expressed fear that such targeted assaults could become "the new normal" in conflict zones.