The 73-year-old man was the only one gored during the first day of the annual running of the bulls in Pamplona, CNN reported.
A 21-year-old Japanese runner who suffered back injuries when he was dragged by his clothing by a bull's horn and a 26-year-old Australian who suffered a knee injury were also taken to a hospital.
Three other Spaniards, ages 19 to 49, were sent to a hospital with shoulder, rib or wrist injuries, officials said.
Another 72 people were treated for minor injuries at the scene by the Red Cross, officials said.
CNN said there have been 15 deaths in the annual running of the bulls since record-keeping began in 1924.
The annual event began 400 years ago and it has drawn crowds from throughout the world since author Ernest Hemingway wrote about it in his 1920s novel "The Sun Also Rises." A statue of Hemingway has been erected outside the bullring.
The running, which lasts only minutes, starts at 8 a.m. for eight consecutive days.
A weeklong fiesta, named for Pamplona's patron saint, San Fermin, features concerts, parades and amusement park rides.