Several men were accused of murdering the man's son and one other man in 2016. One of the defendants died in the blast and several others were injured.
A man blew himself up during a murder trial in southeastern Ukraine on Thursday, killing himself and a defendant who was on trial for allegedly murdering the attacker's son. Nine people, including several other defendants, were injured in the blast.
The trial was taking place in the city of Nikopol, some 240 kilometers (150 miles) from separatist provinces in eastern Ukraine.
The defendants stood accused of murdering two men in 2016 after they allegedly opened fire on the victims' car with automatic weapons.
While Thursday's hearing was taking place, the father of one of the victims entered the courtroom before pulling out and detonating two hand grenades.
The man was immediately killed in the blast, while one of the defendants later died of his injuries in a nearby hospital. Several court officials and guards were also among the injured.
Ukraine has seen an alarming increase in the number of weapons illegally sold in the country since the outbreak of armed unrest in eastern Ukraine in April 2014.
Police have seized explosives, including hand grenades, smuggled from conflict regions to the rest of the country.
amp/msh (AFP, dpa)