The CD4/CD8 ratio is an indirect marker of immune activation, immune senescence, and inflammation in HIV infection. We performed a prospective study of the CD4/CD8 ratio evolution in 245 virally-suppressed (median, 55 months) HIV-infected patients (29% females) who had switched to four dual antiretroviral regimens. At baseline, the median CD4/CD8 ratio was 0.71 (interquartile range, IQR, 0.46–0.97), associated with duration of HIV infection, nadir CD4+ cell count, and AIDS diagnosis. It was lower in the case of hepatitis C virus coinfection and cardiovascular disease (p = 0.09), but the ratio was higher in patients with chronic kidney disease, proteinuria, or osteoporosis. At 48 weeks, the median CD4/CD8 ratio increased by 3% (+0.02; IQR, –0.07, +0.09; p = 0.07); greater improvement was observed in patients with lower baseline ratios and previous AIDS diagnosis. The slope of increase was slower in patients with the highest baseline values. Also, there were no differences in the CD4/CD8 ratio increase according to type of dual regimen, after adjusting for baseline and HIV-related values. In conclusion, CD4/CD8 ratio increase is observed during suppressive dual regimens, and its extent is related to baseline values and previous HIV-related factors. Longer duration on antiretroviral therapy and drug toxicity could affect the evolution of this marker in the presence of comorbidities.