MD Abu Selmia and other staff members were detained in November when Israeli forces raided the Al-Shifa Medical Complex in Gaza before ransacking and destroying the largest medical facility in the strip.
Abu Selmia was among 55 Palestinian detainees from Gaza released on Monday, said the director of Nasser Hospital in southern Gaza Nahed Abu Taima.
Abu Taima confirmed that all but five were taken to Nasser Hospital, where mass graves were recently discovered after Israeli attacks on the facility, for medical checkups.
The others were taken to Al-Aqsa Martyrs Hospital in Deir Al-Balah.
Palestinian health officials say Israeli attacks and raids on hospitals forced most medical facilities to shut down or dramatically reduce services, recklessly endangering civilians.
In video comments aired by Palestinian media following Abu Selmia’s release, he accused Israeli authorities of mistreating Palestinian detainees.
“They are subjected to daily physical and psychological humiliation,” Abu Selmia said.
Abu Selmia said he was put through "severe torture" during his detention, which left him with a broken thumb.
"Prisoners are subjected to all kinds of torture," he told a press conference.
"Several inmates died in interrogation centres and were deprived of food and medicine."
"For two months no prisoner ate more than a loaf of bread a day," added Abu Selmia.
The medical chief said no charge had ever been made against him.
The Gaza European hospital in Khan Younis said the head of its orthopaedic unit, Bassam Miqdad, was also among those freed on Monday.
In May, Palestinian rights groups said a senior Al-Shifa surgeon had died in an Israeli jail after being detained.
Lawyer Khaled Mahajneh, who was able to visit one of the detainees about two weeks ago in Israeli Sde Teman prison, said the detention administration keeps the detainees shackled and blindfolded 24 hours a day.
"There are those whose limbs were amputated, and bullets were removed from their limbs without anaesthesia," added Mahajneh.
A detainee, Faraj Al-Samuni, said at the moment of his release that detainees in the occupation prisons, especially those from Gaza, suffer from tragic and unbearable circumstances, according to WAFA news agency.
The occupation forces had detained him on 16 November from his home in the Al-Qarara area, east of Khan Younis, in the south of the Gaza Strip, Al-Samuni explained.
He was transferred to the Sde Teman detention centre and placed in a tent with 30 detainees.
Al-Samuni said detainees are subjected to various types of torture, abuse, and assaults.
Israel still declines to disclose the number of detainees from Gaza and carries out the crime of enforced disappearance against them.
Since 7 October, the Israeli army has detained more than 9,450 Palestinians from the West Bank and East Jerusalem and hundreds from inside the 1948 Green Line.