A 64-year-old woman died in hospital after she lost control of her car, which struck a large boulder in Chintin last Tuesday.

Police believe the woman's grey Mazda wagon was travelling east on Wallan-Romsey Road when the smash occurred about 8.30am.

The woman, from Chintin, was flown to The Alfred hospital but died on Wednesday.

Senior Constable Roger Barr, of Lancefield police, said the cause of the crash was not yet known, though there had been rain earlier in the day.

The accident was on a sweeping bend about 100 metres west of Darraweit Valley Road.

"Our concern at the moment is the number of serious accidents on smaller roads. They are much narrower; more trees shade the roads and they're often more slippery," Senior Constable Barr said.

Leading Senior Constable Mark Tepper, of Macedon Ranges highway patrol, said motorists needed to be mindful of road conditions.

"It's the same thing over and over. People think they know the roads, but road conditions change. People need to drive to the conditions. You may be able to drive 100km/h when the road is dry, but when it's wet you have to adjust your driving accordingly."

The Chintin fatality follows two deaths last month.

Just before 3pm on January 15, a 20-year-old Bendigo woman, who was a back-seat passenger, died when the car she was in left the Daylesford-Malmsbury Road at Denver.

Just after 3pm the same day, a motorcycle and a car collided at the intersection of Romsey and Springfield roads in Springfield. The rider, a 25-year-old Ballarat man, died.

Denver is in the Bendigo police service area, while Springfield and Chintin are in the Macedon Ranges service area.

"We recorded two fatalities for the whole of 2011 and we've reached that already," Leading Senior Constable Tepper said.

Information to Crime Stoppers, 1800333000 or visit their website here.