Background: In the 21st century, laboratory service has become the pioneer of patient’s healthcare. Although improvement in technology and innovations has reduced human work with computerized machines, then also errors occurs at various phases of total testing process. In this study, we tried to observe and evaluate the errors taking place in total testing process and how such errors could be minimized, results into decreased turnaround time and thus improve the quality of total testing process. Aims: To observe, analyze and evaluate the errors taking place in total testing process of biochemistry section of clinical chemistry laboratory before and after intervention. Method: The study has been conducted in a tertiary care super specialty teaching hospital. An observational and interventional study was carried out on the samples collected in OPD collection centre and from different IPD wards received in particularly biochemistry section of clinical chemistry laboratory for a period of one year in different phases. Result: The study data shows that after intervention the pre-analytical, analytical and post-analytical errors got reduced to almost 1/3rd in case of OPD samples and ½ in case of IPD samples in comparison with before intervention. Conclusion: From the study we also conclude that the single intervention in terms of training might not produce sustainable reductions in error as per the requirement. So, to have best results from training, there should be periodic sessions and training using different methods to focus on the problems.