Initial jobless claims jumped 12,000 from a revised 282,000 last week, and came in well above analyst expectations at 294,000, well above the average for 2015 so far.
The 4-week average is little changed, up to 282,750 which is nearly 25,000 below the month-ago comparison.
Analysts had forecast claims slipping to 280,000. The Labor Department says there was nothing unusual in the state-level data.
Continuing claims, in data for the April 4 week, fell 40,000 to a new 15-year low of 2.268 million while the 4-week average fell 33,000 to 2.329 million.
The unemployment rate for insured workers is unchanged for a third week at 1.7%.