CCR5 antagonists may provide a well-tolerated switch option for patients experiencing tolerability or toxicity of their antiretroviral regimen. We analyzed stored samples from patients undergoing planned treatment interruptions for reasons other than virological failure, in order to analyze tropism evolution during fully suppressive antiretroviral therapy (ART). Two of 37 patients showed evidence of switching. Tropism switching after suppressive ART was uncommon in this cohort. Pretreatment human immunodeficiency virus (HIV) RNA tropism testing may help guide the switch to CCR5 antagonists in patients with undetectable HIV RNA.