Many of those killed in the blast were lawyers and journalists who had gathered at the hospital to mourn and report on the death of lawyer Bilal Kasi, who had been gunned down earlier in the day and his body deposited in the morgue.
The explosion at the hospital in Quetta on Monday also injured 112 others, said Rehmat Baloch, the health minister of Balochistan province in the western part of the country.
"It was a scene of utter horror and devastation in the courtyard hospital," Wall Street Journal reporter Saeed Shah told CNN's Max Foster from Islamabad. "There were bodies strewn everywhere, bleeding lawyers trying to get up."
The explosion rocked the emergency ward of the civil hospital.
Jamaat-ul-Ahrar and ISIS have claimed responsibility for Monday's attack at the hospital.