LONDON Dayron Robles of Cuba did not finish the 110 meters hurdles final in which he was defending his Olympic title and Brazilian Cesar Cielo failed to win a major 50 meters freestyle race in the pool for the first time in four years.
Argentina did not get the late burst of medals from team sports they had in Athens in 2004 and Beijing in 2008 to boost a meager total at the 2012 London Games.
Latin America will be expecting better in Brazil in four years time.
A medals haul of 17 and 22nd place in the table was not a bad return for the future Olympic hosts, even if Brazil failed to win some almost-certain gold medals while picking up others unexpectedly.
"In the same way that there are negative surprises, so there are also positive ones," Brazil team chief Bernard Rajzman told Reuters.
Brazil will be looking for far more than three gold medals, five silver and nine bronze when Rio de Janeiro is host in 2016.
The region's biggest and most populous country was let down in the sports where they have the best training programmes and facilities but can take heart from surprise results in such disciplines as boxing, judo and gymnastics.
Brazil are targeting a place among the top 10 on the medals list at the Rio Games and their haul of medals in London is a national record and an improvement on Beijing, although the golden total stayed the same.
If Britain is an example to go by, Brazil can beef up their sports programmes and prepare to do far better than any Latin American country has ever done at the Olympics when the extravaganza is held in South America for the first time.
The large Spanish and Portuguese speaking region, taken as a whole, has proportionately done poorly at the Olympics, not least Brazil's great rivals Argentina who picked up a paltry four medals in London, worse than the six in Beijing.
Sebastian Crismanich's victory in taekwondo was Argentina's first individual gold medal since Delfo Cabrera won the marathon at the previous London Games in 1948.
The region has never been noted for investing in a big way in sport outside soccer apart from the small island of Cuba who have usually punched above their weight.
In London, Cuba suffered a black Wednesday during the second week when Robles, troubled by back pains all season, pulled up halfway through the high hurdles final he had won in Beijing.
On the same day, compatriot Lazaro Borges was a medal candidate in the pole vault after finishing second at the World Championships in Daegu last year. Instead, he broke his pole, failed to settle into his rhythm with a replacement and failed to go beyond the qualifying round.
However, Cuba were Latin America's top ranked nation in 15th place with five gold medals, three bronze and six silver after their boxers won two titles having surprisingly failed to pick up any in Beijing.
Colombia were third among the Latin American teams with eight medals including one gold and three silver after successes in cycling and Caterine Ibarguen finishing second in the women's triple jump.
Mexico were right behind them with one less bronze having shone in archery and diving, and winning a shock gold in soccer with victory over favorites Brazil in the final.
Isolated results gave Venezuela their first gold medal for 44 years in any sport with Ruben Limardo's victory in fencing and Guatemala a silver for Erick Barrondo in the 20km walk.
(Additional reporting by Pedro Fonseca; editing by Michael Holden)