Hushovd, who rides for Cervelo, finished the 93.2-mile leg in 3 hours, 36 minutes, 20 seconds. Daniele Bennati of Italy and Grega Bole of Slovenia crossed the line next in the same time as Hushovd.
“I was motivated for this stage, I knew this climb,” Hushovd said. “I hung on and then the team did a great job for me.”
Hushovd said taking a conservative approach on the steep descent from the peak of Cresta del Gallo near the close of the stage was key.
“Everybody said it was dangerous and technical, so I stayed easy there and on the bumps afterward,” he said.
"In the end the Cervelo Test team did a great job for me so I'm really, really pleased for myself and for the whole team." His Cervelo teammate, Spain's Carlos Sastre, also hailed the team effort that led to the first stage win for the Swiss outfit in this year's event.
He said "very few sprinters" were able to keep up during the final climb.
"That meant our team ... was able to control the head of the race so Hushovd could fight for victory in the sprint," said the 2008 Tour de France winner, who finished with the main group.
The stage was marked by an early breakaway by three riders — Germany's Markus Eichler, France's Freddy Bichot and Spain's Juan Javier Estrada Ruiz.
They built up a lead of more than 9 minutes but they were caught on the final hill climb with about 18 kilometers to go.
Gilbert, who rides for the Omega Pharma team, finished with the same time as Hushovd and retains his lead in the overall classification, which he first claimed from Britain Mark Cavendish after winning Monday's third stage.
He is 10 seconds ahead of two Spaniards, Igor Anton and Joaquin Rodriguez.
Friday's seventh stage takes the riders 187.1 kilometers from Murcia to Orihuela, and includes just one third category climb.
The 21-stage Tour of Spain, which began on Saturday with a team time trial through the streets of Seville, wraps up in Madrid on Sept. 19.
Gilbert held on to the leader’s red jersey once again after finishing sixth behind Allan Davis of Australia and Filippo Pozzato of Italy in the same time as Hushovd.
The Belgian cyclist for Pharma-Lotto holds a 10-second lead over Spanish duo Joaquin Rodriguez and Igor Anton, while Vincenzo Nibali of Italy trails by 12 seconds. Gilbert’s time is 22:36:26.
Frank Schleck of Luxembourg was 66th in the same time as Hushovd to stay 50 seconds behind Gilbert while defending champion Denis Menchov of Russia placed 23rd. He’s 1:11 off the red jersey.
The stage Friday is a relatively flat, 116.3-mile leg from Murcia to Orihuela.
