Federal judge Carlos Branca ruled there was insufficient evidence to try Maradona for allegedly switching urine samples with another player who tested positive after a match for Boca Juniors last season.
When he testified before the judge last month, Maradona admitted to taking cocaine but denied having switched samples.
The 36-year-old has been traumatised by the imprisonment of his manager and close friend Guillermo Coppola on cocaine-dealing charges, which could land him a jail term of up to 20 years.
Police found a pound (400 grams) of cocaine in a flower vase at Coppola's home three weeks ago. Coppola insists the drugs were planted.
The hero of Argentina's 1986 World Cup victory, twice banned from the sport for drugs, has said this latest in a long series of scandals has sapped what strength was left in him.
"They have beaten me. It's hard to accept because I've been a fighter all my life, but that's it: I've taken off my gloves, I've no more strength to fight," Maradona said recently.
A 20-year-old woman identified only as Valeria launched a paternity suit earlier this month against Maradona, who is married with two daughters.
Her lawyers expect the court to order genetic tests within a few days which they say will prove Maradona is the father of the seven-month-old girl.
Maradona lost a paternity suit four years ago when a judge ruled he was the father of a boy in Naples, where he played for Napoli in the 1980s. He refused to submit to genetic tests in that case, but his lawyers have not commented on the latest suit.
He also threatens to quit professional football. He has not played in a game for three months but trained with his Boca Juniors club on Tuesday.
Maradona showed up to practise for about half an hour in what he described as a show of solidarity with his coach, Carlos Bilardo, Coppola and his fans.
"I didn't come thinking about playing again but rather for Carlos, I came for Guillermo, I came for the Boca boys and for all the people who love me."
In the afternoon, he appeared to leave his troubles behind by appearing on a television programme with his wife and dancing, ironically, to the Elvis tune "Jailhouse Rock".
The Spanish First Division club Valencia is seeking the return of Brazilian striker Romario to play for the side and Johan Cruyff as coach to replace Luis Aragones.
"Cruyff is being sought," spokesman Manuel Mas said. "Whether Romario returns would depend on the new coach, but it's being discussed."
Valencia accepted the resignation of Aragones within hours of the side defeating the Turkish side Besiktas 3-1 in the Uefa Cup on Tuesday.Reuse content