Temperature and frequency effects on fatigue crack growth rate have been modelled. The "stress intensity factor"-biased Arrhenius equation and a result from the "two-stage zone" model have been incorporated into the present model. Subsequently, temperature and frequency effects on fatigue crack growth in unplasticized polyvinyl chloride (uPVC) were studied over a temperature range 15-55-degrees-C and a frequency range 0.01-10 Hz. Data for PVC taken from the literature were also included for analysis. It was found that the predicted values, from the proposed model are in good agreement with experimental results.