Barros started racing in the age of 8, when he won on his début in the Brazilian minibike championship. In the next two years, he was twice Brazilian moped champion. In 1981, he was the Brazilian 50cc Champion, and in 1985 he won the title of Brazilian's 250cc category. The year of 1986 saw him international début in the 80cc category -- he lied about his age so he could race at the Spanish Grand Prix at the age of 15. He finished the championship in thirteenth place, scoring 6 points. In 1987, he also raced the 80cc championship, finishing seventeenth, scoring 8 points.
In 1988, Barros made his first race on the World Championship 250cc category, scoring no points. That same year, he was 3rd in the Latin American circuit of that same class. The next year, he finished 18th in the World Championship, scoring 30 points.
500cc and MotoGP
In 1990, Alex Barros was the youngest rider in history to join the top motorcycling category, the 500cc, at the age of 20. In his first year, he was 12th overall, with 57 points. Notable results included 8th in the United States and Germany, and 5th in the Belgium Grand Prix. Two years later, his first podium: a third place in the Netherlands.
The year of 1993 saw his breakthrough as he joined the Suzuki team. After qualifying third in the US Grand Prix, Barros had his first victory in Spain, finishing that year's world championship in sixth place. His team-mate Kevin Schwantz was that year's champion. The following year, Barros scored in all but one the races. 1996 saw his best performance yet, finishing the championship at fourth, a feat he repeated in 2000, 2001 and 2002. In 2002, the first of MotoGP (with engine displacement capacity increased to up to 990cc) he scored 206 points, eleven points behind second place. 2003 was a difficult one for Barros due to injuries, but in 2004, he once again finished the championship in fourth, in a season dominated by Valentino Rossi, Sete Gibernau and Max Biaggi. In 2005, Barros returned to the top of the podium, at the Portuguese Grand Prix, however he did not mount a lasting championship challenge, and was not offered a ride for 2006.
For 2006 he was hired by the Klaffi Honda team in WSBK, paying around £100,000 of his own money to fund the ride. After a satisfatctory debut weekend with 2 top 10 finishes, he took a pair of podium finishes at round 2 in Phillip Island, and a second and a fourth in round four at Monza. At Brands Hatch he failed to qualify for Superpole, but bounced back from 18th on thei grid to take a pair of top 10 finishes. The wet meeting at Assen was a disappointment for Alex, especially as he is a wet-weather expert.
His season has been characterised by poor starts, but despite this he is the second highest Honda rider in the championship in sixth place after 10 rounds, behind former champion James Toseland. At Imola he took his first WSBK win, and followed it with a 2nd in race 2.