Dr Douglas Gwatidzo, head of casualty at the Harare hospital where Tsvangirai was being treated, said the prime minister had head injuries and chest pains, but was in stable condition.
State television showed pictures of Tsvangirai in a neck brace, which Gwatidzo said was being used to keep him comfortable.
"We might release him today or tomorrow," Gwatidzo told reporters gathered at the hospital. Ian Makone, a secretary to the prime minister and member of his Movement for Democratic Change party, said Tsvangirai was "very devastated by the death of his wife".
The crash happened on Friday evening on the outskirts of the capital on a decrepit road notorious for accidents. Like many in Zimbabwe, it is in poor condition because it has not been maintained.
A US Embassy official said that the truck involved was transporting medicine for Aids patients donated by the US government. It was driven by a Zimbabwean contracted by the US.
State television said the truck swerved on an uneven stretch of road. Tsvangirai’s spokesman James Maridadi earlier said the Tsvangirais’ car sideswiped the truck and rolled at least three times.
The state-run newspaper The Herald reported that the two other people in Tsvangirai’s car – the driver and a bodyguard – were also injured. The paper added the driver and occupants of the truck were taken to a police station, but it was unclear whether they had been arrested.
Police spokesman Superintendent Andrew Phiri told The Herald the truck may have struck an object on the road before it veered.
Susan Tsvangirai, 50, was pronounced dead soon after arrival at a clinic about 25 miles from Harare, Makone said. He said her children were flying to Zimbabwe from Australia and South Africa and funeral arrangements were being made.