A woman has been airlifted to Canberra Hospital after falling between two boulders while bushwalking.

Emergency services were called to a national park about 37 kilometres east of Goulburn yesterday afternoon after a woman became trapped and suffered possible spinal injuries.

She was treated at the scene by a doctor who was also bushwalking in the area, before Police Rescue arrived.

Another two bushwalkers had to be treated for heat exhaustion.

Police are reminding people to be prepared for hot conditions.