AN ELDERLY woman has died after a crash near Wollongong, marking the first death on NSW roads in the Christmas toll period.

Police say the 79-year-old woman was travelling with her husband and another married couple, aged 73 and 74, when their car collided with another car in Mount Ousley just after 1pm (AEDT) yesterday.

Police say the woman was taken to Wollongong Hospital but died a short time later.

Her 80-year-old husband remains in a serious but stable condition with suspected spinal fractures.

Police have called for witnesses to contact Southern Region Crash Investigation Unit or Crime Stoppers.

The death brings the national toll to four - one each in NSW, Tasmania, South Australia and Victoria.