The revised jobless rate in April was 9.2 percent, the Employment Security Department reported Wednesday.
The state hasn't seen the unemployment rate at 9 percent or below in more than two years, and it has trended as high as 10 percent. A year ago, it was 9.6 percent.
Dave Wallace, the department's acting chief economist, said he was disappointed by the numbers, especially since they came just one month after the same jobs report showed growth in a broad range of sectors.
"We certainly hope that this is a deviation as opposed to a trend," Wallace said.
Economic forecasters point to a range of factors that could turn stagnant employment into a trend.
Wallace said the direction of gas and commodity prices could affect the state's economy along with international influences such as the ongoing financial crisis in Europe and an economic slowdown in China.
In May, the state lost jobs in wholesale and retail trade, financial activities, transportation, warehousing and utilities, education and health services and manufacturing.
Sectors that posted job gains included leisure and hospitality, professional and business services, construction and government.
Unemployment can still fall in Washington despite the lost jobs if those who are looking for work get discouraged and stop looking or leave the state.
State officials said in Washington an estimated 306,919 people were looking for work in May. There were 208,582 people receiving unemployment benefits from Washington last month.
Officials said the state has added 49,400 private sector jobs during the past year.
Unemployment numbers for the state's counties will be released next week. In April, the jobless rate in Snohomish County dropped sharply to 9.6 percent, but much of the change was attributed to discouraged job seekers who had stopped looking.
The Associated Press contributed to this story.