Global shipments of personal computers (PCs) are expected to see their "most severe yearly contraction on record" in 2013, according to research firm International Data Corporation (IDC).
The firm said sales of PCs would fall by 10.1% this year, worse than the previous estimate of 9.7%.
PC sales have fallen for the last six quarters, the longest historical drop.
Global shipments of PCs have been hurt by the growing popularity of tablets and smartphones.
"Perhaps the chief concern for future PC demand is a lack of reasons to replace an older system, " Jay Chou, a senior research analyst with IDC, said in a statement.
Worldwide shipments would continue to fall in 2014 but at a slower pace, said IDC.
In July this year, the firm said it was still looking for some improvement in growth during the second half of the year. It has now reversed that view.
It explained that interest in PCs had remained limited, "leading to little indication of positive growth beyond replacement of existing systems".
One key growth area for PC sales has been emerging markets, but IDC said interest had been falling there and that shipments would likely decline into 2014.
Earlier this year, research firm Gartner said that a greater availability of inexpensive Android tablets was attracting first-time consumers in emerging markets and hurting PC sales.
On the upside, the commercial market is faring better than the consumer market this year.
Commercial shipments are expected to fall by 5% in 2013, from a year ago, compared to a nearly 15% drop for consumer sales, according to IDC.
The relative stability in the commercial market was down to "a mix of more stable PC investment planning, a smaller impact from tablets, and to replacements of Windows XP systems before the end of support planned for 2014," the firm said.
"However, the long-term outlook for the two markets is not significantly different, with a small decline projected for both consumer and commercial segments in 2014 with near flat growth in the longer term."