frequency of errors in clinical laboratory practice

background and objective: laboratory errors are one of the major factors that affect the diagnosis, prognosis, treatment and monitoring in patients.the objective of study is to evaluate the frequency and type of errors in different phases of testing at the pathology department of the shalamar hospital, lahore and to evaluate the causes of errors. methods: this observational study was carried out in shalamar hospital laboratories lahore from 1st july 2011 to 31st december 2011. errors detected and documented on daily basis.  results: a total of 127,500 samples were received and processed during the six months period. out of the total samples, 1530 (1.2) errors were detected. among all errors pre-analytical errors were most common, with a frequency of 70.4%, post-analytical 17.5% and analytical 12.1%.  conclusions: our study demonstrates the types and frequencies of errors. it is very important to monitor the all phases so to reduce the frequency of error for better reporting of lab results, ultimately which ensures the patient well-being.