Ultrapure, recombinant Taq DNA Polymerase is reversibly complexed with anti-Taq monoclonal antibody that blocks replication activity of the enzyme at moderate temperatures. Our carefully selected anti-Taq antibodies have high thermal stability, providing protection against non-specific primer extension from room temperature to 70°C. The polymerase activity is restored during the initial denaturation step when amplification reactions are heated at 94-95°C for two minutes. Formation of complexes between Taq DNA Polymerase and an anti-Taq antibody forms a basis for automatic “hot start” PCR, which allows for the assembly of PCR reactions at room temperature. High stability of the complexes allows for the enormous increase of PCR specificity, sensitivity and yield in comparison to the conventional PCR assembly method. Automatic “hot start” PCR is a fast and convenient method when assembling multiple PCR reactions. Both increased specificity and reduced mispriming improve multiplex PCR. Thermostable Taq DNA Polymerase replicates DNA at 74°C and exhibits a half-life of 40 min at 95°C (1,2). Catalyzes the polymerization of nucleotides into duplex DNA in the 5′->3′ direction in the presence of magnesium ions. Contains the 5′->3′ exonuclease activity. Lacks the 3′->5′ exonuclease activity. Adds extra A at the 3′ ends. Perpetual Taq DNA Polymerase is recommended for use in PCR and primer extension reactions at elevated temperatures to obtain a wide range of DNA products up to 10 kb.