Tuesday's stampede occurred as people tried to leave a stadium following a speech by Ali Abdullah Saleh, the president. More than 80 people were injured.
The venue was crammed with about 150,000 people who had flocked to the rally in the run-up to the September 20 presidential and local elections and more thronged the streets outside.
Reuters reported several bodies lying in the grounds of the stadium in the southern province of Ibb.
Ambulances and police cars have taken the injured to hospital.
A reporter at the scene said: "The stadium was very crowded, people were standing on the ground as well as the bleachers.
"After the president left, people rushed to get out of the stadium and that's when the stampede happened."
President Saleh has held a series
of election rallies
A Yemeni official said the government would compensate families who lost a relative in the crush.
Ibb province is about 170km south of the capital, Sana.
In Taiz province, 250km southwest of the capital Sana, at least four people were killed and 10 injured on Monday in a stampede at a similar election rally, government officials said.
Saleh, the poor country's long-serving president and the front-runner in the poll, is touring Yemeni provinces to get support for his campaign.