For more than 15 years, Dr. Robert Mellor has traveled to Latin America giving free medical treatment to Mexican or Guatemalan natives.

Mellor is one of 25 local medical professionals who left this week for Senahu, Guatemala, where he will spend several days treating more than 500 patients who can't afford or wouldn't have access to medical treatment otherwise.

"They're poor as poor can be," said Mellor, an ear, nose and throat doctor from Layton.

Mellor is the president of Utah Medical Outreach, a nonprofit corporation that makes semiannual trips to Guatemala providing medical, surgical and humanitarian services. He started making medical humanitarian trips in the late 1980s to Mexico. This will be the fourth time he has gone to Senahu with UMO.

Many of the people the group serves don't seek medical treatment because they can't afford to travel into the country's bigger cities for such treatment.

"They can't afford to leave their job for the two weeks it takes to go just get a cold checked out," Mellor said.

Mellor said he and his group try to bring specialty care closer to the poor residents. Through the years group members have accumulated more experience and more portable gear, which allows them to venture farther away from big cities. Mellor said the more primitive the area, the greater the needs.

The group has developed what Mellor calls a "MASH" or "Mobile Army Surgical Hospital" equipped with portable surgical beds, tables, anesthesia machines, microscopes, cataract machines and more.

"We just load it onto a big chicken bus and just head off to the mountains," he said.

After arriving in Guatemala by plane, the doctors then take a 12-hour bus trip to Senahu. There they set up temporary operating rooms at a health clinic, and the medical team sees patients for four or five days. The team starts work around 7 a.m. each day and ends between 9 and 10 p.m.

"It is just so much fun," he said. "I mean it's a ton of work . . . but there's just such a tremendous feeling of joy and satisfaction when you're done. I mean the people basically have nothing and yet you go, and they feel like you're giving them so much, and you end up getting back so much more than you ever give."

From eyeglasses to hearing aids, the doctors take donated supplies with them to give to their patients during the trip.

"You'll see these men wearing these 1950s glasses with swirly things on them, and they are just grateful to see," Mellor said.

Mellor takes artificial bones with him to use when performing surgeries. While in Guatemala, he will do facial plastic surgery, repair cleft lips and palates and heal a lot of ear problems.