The aim of this study was to determine the coreceptor tropism by performing genotypic HIV-1 tropism testing in a cohort of patients perinatally infected with HIV-1 and exposed to antiretroviral therapy. Genotypic coreceptor tropism was determined in patients with HIV-1 RNA<100 copies/mL using PBMC samples by gp120 V3 sequencing followed by geno2pheno interpretation (set at a false positive rate [FPR] of 20%) and in patients with ≯100 copies/mL using plasma samples (set at a FPR of 20%), according to European guidelines. Out of 55 patients, 50 had an HIV-1 subtype B strain, and mean (SD) age was 18.2 (4.6) years. The median duration of antiretroviral therapy was 13 years (range, 3-23). Thirty-three (60%) patients harbored the R5 virus. At the time of the testing, the median CD4+ T lymphocyte cell count and percentage were 705 cells/mm3 (474-905) and 32.5% in group R5 and 626 cells/mm3 (450-755) and 31.7% in group X4/D-M, respectively. The nadir of CD4+ T-cell count in groups R5 and X4/D-M were 322 cells/mm3 (230-427) and 340 cells/mm3 (242-356), respectively. These differences were not statistically significant. Fifteen patients had HIV-1 RNA ≯50 copies/mL. The median HIV-1 RNA and HIV-1 DNA were comparable in both groups without a statistical difference. The study provides an overview of the prevalence of coreceptor tropism in a cohort of patients who were vertically infected with HIV-1. The high prevalence of X4/D-M-tropic strains may simply reflect the long-term exposure to HIV.