Lead author Roberta Wyn of the University of California, Los Angeles, said the study found women without a high-school diploma were nearly four times more likely to be uninsured as women with a college degree.
Wyn and colleagues found that in California in 2007, 2.5 million women ages 18-64 were uninsured at some time of the year.
The study found 75 percent of women with a college degree had health insurance from an employer, compared with 49 percent of those with a high-school degree and 23 percent of those who had not graduated high school.
In addition, 42 percent of the women without a high-school degree did not have health insurance, in contrast to 11 percent of college-educated women, the study said.
"Health insurance coverage and education are clearly linked," Wyn said in a statement.