Apple's iPhone took 19.2% of the US market for smart phones in the first quarter of 2008, according to research firm IDC.
That was down from 26.7% of smart phones sold in the fourth quarter of last year, which included the holiday shopping season, IDC, quoted by an Associated Press report, also said.
Much of the slack was picked up by Research In Motion's BlackBerry, which took 35.1% of the market in the fourth quarter and then 44.5% in the first.
The report further quoted IDC analyst Ramon Llamas as saying the BlackBerry is now strong in the 'prosumer' segment, as RIM has successfully widened the appeal of the device beyond the professionals who have been its core customer group.
IDC did not reveal the total number of smart phones sold in the quarter.
Apple said it sold 1.7 million iPhones in the first quarter, including overseas sales.
Palm, a pioneer in the category along with RIM, also picked up market share in the first quarter, when it grabbed 13.4% of smart phone sales, up from 7.9% in the fourth quarter, IDC said.
No. 4 in market share in the most recent quarter was Samsung Electronics, with 8.6%, up from 5.1% in the fourth quarter, a rise Llamas credited to the availability of the BlackJack on Verizon Wireless.
Motorola, which is struggling in the overall mobile phone market, did poorly in smart phones as well, dropping from a 7.5% share in the fourth quarter to 2.6% in the first, the Associated Press report said.