CXC-chemokine receptor 4 (CXCR4) functions as a receptor for feline immunodeficiency virus (FIV). Although we previously found that a CXCR4 antagonist, T140, inhibited the FIV replication in vitro, it was not effective in cats infected with FIV because of its low stability in feline serum. To resolve this problem, several T140 derivatives have been developed. Here, we examined the efficacy of T140 analogs, TF14016 and TF14013, on the inhibition of FIV infection. These compounds were shown to significantly inhibit the syncytia formation in CXCR4-expressing cells after co-cultivation with FIV-infected cells and the replication of FIV in a feline lymphoid cultured cell line. These results indicated that TF14016 and TF14013 could be useful as antiviral drugs for cats infected with FIV.