Circulating androgens correlate with resting-state MRI in transgender men.

•Lack of general information how cross-sex hormonal treatment impacts resting-state (rs) function.•Transgender men, transgender women, natal men and natal women completed rsMRI.•rsfMRI was similar in transgender men and natal men relative to natal women in the cerebellum and frontal cortex.•The androgenization effect in transgender men in the cerebellum was associated with treatment duration.•Data provide first evidence for masculinization in rsMRI in cross sex hormone treated transgender men.