The objective of this work is to analyze the performance of HDLC Balanced Class of Procedures under saturated, full-duplex transmission on error prone links. This thesis extends work done by Bux et al. [8] by considering errors on both the links. Satellite links have long propogation delays compared to terrestrial links, and hence, have longer error recovery times. For such links, errors in acknowledgements have considerable impact on the throughput. In this analysis, the effect of errors in acknowledgements is taken in to consideration. An analytical approach is used to derive performance measures. The concept of "virtual transmission time" introduced by Bux et al is redefined to accommodate the effect of errors in acknowledgements and used in the analysis. Resulting throughput calculations show how various parameters, (e.g. transmission rate, propagation delay, error rate and packet size), interact and determine the performance. / Master of Science