In a case that has plunged the 56-year-old leader into scandal, Morales had claimed he fathered a child with her which later died, before changing his story to say the child never existed.
A court ordered the leftist president to undergo a test to answer claims by his ex-partner Gabriela Zapata that he is indeed the father of her child.
"Evo Morales is a citizen who respects the law. If the authorities summon him, he will attend," his lawyer Gaston Velasquez was quoted as saying by the newspaper Pagina Siete.
Compounding the scandal, Zapata has also been implicated in an alleged corruption case.
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Zapata is currently in jail pending trial on charges of money laundering, embezzlement and influence-peddling.
A former manager at Chinese engineering group CAMC, she is accused of using her ties to the president to land $560 million in government contracts for the company.
The case exploded just as Bolivia prepared to hold a referendum on whether to change the constitution to allow Morales to run for a fourth term.
Morales, Bolivia's first indigenous president, went on to lose the February 21 vote -- his first electoral defeat in a decade in power.