The next step in the evolution of UMTS is the Enhanced Uplink or high speed uplink packet access (HSUPA), which is designed for the efficient transport of packet switched data. One of the major novelties is the relocation of the scheduling control from the RNC to the NodeB which enables a faster reaction to cell load and radio condition variations. Our contribution is an analytic modelling approach for the performance evaluation of the UMTS uplink in a single cell with best-effort users over the enhanced uplink and QoS-users over dedicated channels. The model considers two different scheduling disciplines for the enhanced uplink: Parallel scheduling and one-by-one scheduling. The model also considers the effect of power control errors and other-cell interference fluctuations as well as multiple dedicated channel service classes.