The reaction kinetics of single-stranded RNA replication were investigated by means of analytical and computer simulation methods. A model reaction mechanism is proposed that is in accord with the extensive experimental data available for the replication of various templates by the enzyme Q beta replicase. Despite the complexity of this mechanism, conventional concepts of steady-state and dynamic enzyme catalysis and plausible values of the rate and stability constants for the elementary reactions suffice to provide detailed understanding of RNA replication kinetics. The main features can be described with simple formulas that are analogous to traditional descriptions of enzyme kinetics.