A racecourse in County Durham has one of the highest number of horse deaths in Britain, according to an animal rights group.
Animal Aid says 11 horses have died at Sedgefield Racecourse in just 17 days of racing since March 2007.
The Kent-based organisation has urged course owners to improve conditions in an effort to cut the number of deaths.
The racecourse said it was "impossible to eradicate completely" the risk to both horses and jockeys.
Animal Aid horse racing consultant Dean Stansall said: "The horses at Sedgefield have died by various means. Some broke their legs, some of them broke their necks and other just collapsed and died on the course from exhaustion.
"We found that on average, when we looked at all 59 British racecourses over the past year, one or two horses may have died.
"But to have 11 horses die on a racecourse and in just 17 days racing, we think there must clearly be a problem there.
"Sedgefield is Britain's most lethal racecourse by far."
A spokesman for Sedgefield Racecourse, which is owned by Staffordshire-based Northern Racing, said: "Horse racing is dangerous.
"Whether jumping fences or racing on the flat at up to speeds of 45mph, it is impossible to eradicate completely the risk to both horses and jockeys.
"Occasionally, and despite a total commitment to safety incident may occur.
"This does not reflect upon the racecourse's commitment toward or its ability to stage horse racing in anything other than as safe an environment as possible."
Animal Aid was founded in 1977 and is a not-for-profit organisation run by volunteers.
Northern Racing owns nine courses, including Newcastle, Chepstow and Uttoxeter.