Carl and Clarence Aguirre, the 2-year-old twins who were joined at the head until five weeks ago, should be walking by Christmas, their pediatrician says.

"That's the promise I made to their mother, and it's looking good," Dr. Robert Marion (search) said Thursday. "It could be Halloween, the way things are going."

Marion visited with the boys as they returned to the Children's Hospital at Montefiore Medical Center (search) in the Bronx for a checkup. They were separated there Aug. 4, but were later moved to Blythedale Children's Hospital (search) in Valhalla for physical therapy and other care designed to catch them up to normal development.

Marion said the boys have shown no neurological impairments from the operation and vital signs are fine.

Their mother, Arlene Aguirre, who brought them to New York from the Philippines a year ago, said the boys were "much better now because they're very active."

"They're playing together a lot," she said.

Marion said both boys have shown the desire to stand up, but their neck muscles aren't yet strong enough to support their heads. For that reason, they are still carried like infants.

Marion said there is some concern about the twins' reluctance to talk beyond a few favorite words, but he believes it's a combination of the lack of stimulation as infants and "just being twins," who are known to talk later than other children.

The surgery Aug. 4 climaxed a number of gradual operations over 10 months, a departure from the more common marathon operations that have separated other conjoined twins.