Serum oestradiol concentrations were determined in trans women with HIV taking feminizing hormone therapy (FHT) and unboosted integrase strand transfer inhibitor-based ART (n=8) versus trans women without HIV taking FHT (n=7). Among participants, the median oral oestradiol dose was 4 mg (range 2-6 mg). Six trans women with HIV were taking bictegravir/emtricitabine/tenofovir alafenamide and two were taking dolutegravir/abacavir/lamivudine. All oestradiol concentrations were not significantly different between groups. Eleven (73%) participants had target oestradiol concentrations in the range 200-735 pmol/L at C4h (75% among women with HIV, 71% among those without HIV). However, further research is needed with larger sample sizes to fully understand the impact of HIV and ART on FHT in trans women with HIV.