An anti-Tat hairpin ribozyme and a TAR RNA decoy were combined in one molecule. The chimeric molecule strongly inhibited HIV-1 replication (measured as changes in p24 levels in viral replication assays). The inhibitory action of the ribodecozyme (85%) was significantly greater than that shown by ribozyme and a non-catalytic variant carrying the functional decoy RNA domain (55% and 35%, respectively). This represents a significant improvement of the inhibitory efficiency of the ribozyme, suggesting there is an additive inhibitory effect on HIV-1 replication by the catalytic and decoy domains. This strategy could be used to create new inhibitor RNAs with enhanced in vivo performance.