Pharmacists have an essential role in intervening upon hospital prescribing errors (PEs). Electronic prescribing (e-prescribing) systems have been proposed to reduce PEs in hospitals. Measuring satisfaction of technology users is important to enhance system utilisation. This four-step programme of work aimed at: 1) developing and assessing the feasibility of a computerised method to collect PEs from a hospital's e-prescribing system, 2) validating the reasons recorded by doctors and pharmacists for discontinuing medication orders at hospital discharge, 3) investigating, using the developed computerised method, the number, types, severity, pharmacists' impact, and predictors of PEs in the context of e-prescribing system at hospital discharge, and 4) assessing the attitudes of pharmacists and doctors towards e-prescribing systems at three teaching hospitals. A pilot validation study was conducted initially that comprised two steps: electronically extracting discontinued orders from the e-prescribing system followed by structured interviews with doctors and pharmacists who made the discontinuation. To characterise pharmacists' interventions upon PEs, a four-week study was conducted; meetings were conducted within a week of data extraction with pharmacists performing their routine clinical work, who categorised the occurrence, type, and severity of their interventions using a scale. An independent senior pharmacist retrospectively rated the severity and potential impact, and subjectively judged whether any error was a computer-related error (CRE). The emerging results, together with the literature findings, were used to adapt a previously published questionnaire for a survey of pharmacists and doctors. The methodological approach was deemed valid, efficient and feasible. The majority of recorded discontinuation reasons were judged accurate (97,93.3%). The incidence of PEs was 8.4% (n= 664/7920; 95% CI: 7.8%-9.0%). Omission (31.0%), drug selection (29.4%) and dosage regimen (18.1%) error types were the most frequent. There were 18 (2.9%) serious, 481 (76.3%) significant and 131 (20.8%) minor erroneous orders. Most erroneous orders (469,74.7%) were rated as being of significant severity and significant impact of pharmacists. CREs (n=279) accounted for 44% of erroneous orders. Drugs with multiple formulations (OR 2.1,95% CI: 1.25-3.37) and prescribing by junior doctors (OR 2.54,95% CI: 1.08-5.90) were significant predictors of PEs. The majority of pharmacists and doctors agreed that the e-prescribing system improved the efficiency of prescribing and reduced dosage regimen errors. Pharmacists were more satisfied with their e-prescribing systems than doctors. Satisfaction was predicted with more efficiency-related attributes of the e-prescribing system, than those related to the quality of patient care. This work showed that PEs commonly occur even with the use of an e-prescribing system. The high rate of CREs raised a substantial question as to the ability of the eprescribing system to facilitate certain types of PEs, or alternatively, that the working system in a hospital has to be changed and made safer. Pharmacists played an important role in efficiently documenting and preventing PEs before they could reach and possibly harm patients. CREs should be understood by pharmacists who need to complement, rather than duplicate, the strengths of the e-prescribing system.