Police have launched an appeal to help find a woman and her two young son, three days after they went missing from their northern New South Wales home.

Lisa Cross and her sons Luke, 10, and nine-year-old Logan were last seen at their home at Kootingal near Tamworth on Sunday morning.

The 33-year-old's husband reported them missing yesterday, telling police there were no signs his wife was planning to leave.

Sergeant James Parsons says there are concerns for their welfare.

"The information that we've received from her family and friends is that her disappearance is somewhat out of character for her," he said.

"The husband's most distraught and very concerned about Lisa and the children.

"The full circumstances of Lisa's disappearance is still subject to an investigation and it's too early for us to speculate on what may have taking place leading up to her leaving with the children."

Police believe Ms Cross may be travelling to Western Australia with her two sons.

The trio may be travelling in a white Holden Commodore with NSW registration, BIB 16F.