The ComScore results are strikingly similar to last week's Nielsen U.S. report that covered roughly the same period.
The Nielsen survey found that Android had a 38% share smartphone market share in its May report, up two percentage points from three months earlier.
to 27% from 26%, Nielsen said.
Nielsen blogged that the iPhone had shown the most growth in recent months, although ComScore's data indicates otherwise.
Both surveys are considered highly reliable.