Mladic, who was Europe's most-wanted man until his arrest Thursday, made a first court
appearance in Belgrade later that day.
But the hearing, before the Serbian war crimes court, was halted after his lawyer Milos Saljic said he was unable to communicate because he "is in a difficult psychological and physical condition".
But Mladic had confirmed his identity, he added.
Mladic was to undergo medical evaluations and doctors would report on Friday as to whether he is capable of appearing in court, said Saljic.
Deputy war crimes prosecutor Bruno Vekaric, while confirming the hearing had been stopped, refused to comment on the reasons. And he disputed the assessment that Mladic was unable to answer simple questions.
Earlier, he had said it could take up to seven days before Mladic was handed over to the International Criminal Tribunal for the former Yugoslavia (ICTY), although Serbian President Boris Tadic has said that the extradition process is under way.
Mladic, 69, who was in hding for 16 years, faces charges of genocide, crimes against humanity and war crimes.
The indictment cites the Srebrenica massacre, the 44-month siege of Sarajevo, and the creation of camps and detention centres during the 1992-1995 war, all as part of a campaign directed against Bosnian Muslims.
Tadic would not say how and where Mladic was arrested other than that he was captured on Serbian soil.
But Serbian security sources told the AFP wire service that three special units raided a house in Lazarevo, a village around 80 kilometres north of Belgrade, close to the Romanian border early Thursday.
The house was owned by a relative of Mladic and had been under surveillance for the past two weeks, one of the sources added.
Serbian Interior Minister Ivica Dacic said Mladic had been armed with two guns "but he did not have the time to use them".