Adherence to product use in biomedical HIV prevention trials is essential to success. In MTN-017, a Phase 2 rectal microbicide gel trial, participants discussed applicator-inserted gel use in the context of receptive anal intercourse (RAI) with adherence counselors. We analyzed counseling session data to identify barriers to and facilitators of gel use for 26 participants in the United States who used gel with RAI as their first of three study regimens. The most common barriers were finding the gel application process cumbersome, physical discomfort after applying gel, difficulty with BAT-24 dosage regimen, and negative effects of gel on sex. The most common facilitators were incorporating gel use into routines, using gel in anticipation of sex, carrying gel when going out, reminders received via short message service, and ease of gel use. These findings can inform product development and future adherence counseling interventions for rectal gel trials to improve adherence outcomes.