Musicians David Crosby and Graham Nash have postponed a month-long US tour because 65-year-old Crosby is unwell.
The tour may happen this autumn when Crosby (second right) is well
Their website said "medical issues" had arisen for the star, who has previously written about his years of drug use.
The tour was to start on 19 March in Shawnee in Oklahoma, ending at Niagara Falls in New York state on 15 April.
Crosby and Nash are known for their Woodstock-era hits such as Marrakesh Express, collaborating at the time with Stephen Stills and Neil Young.
Stills was to have joined them on a recent tour of Australia, which was also called off because of the health of Crosby, who had a liver transplant in 1995 and who has also battled hepatitis C.
Manager Donald Miller said he "deeply regretted" the decision to halt the US tour.
But he indicated that the concerts were likely to be rearranged for the autumn.