Background: Medication errors constitute a considerable concern for the patients and healthcare professionals. Therefore, in recent years there have been remarkable efforts through research papers to assess the etiology of medication errors. Aim: To review the current literature related to the individual and the organizational factors that contribute to the occurrence of medication errors in the clinical nursing practice. Method and material: A combination of various search terms: medication errors, contributing/etiologic/risk factors, nurses and nursing was used to search through the Pubmed database. For the involvement of an article in the existing review, specific inclusion criteria were set such as published in English the period between January 1990-December 2012. Results: A total of 13 original research articles were included. The contributing factors to the occurrence of medication errors in clinical nursing practice include and system related subcategories. Two tables are provided. The first outlines the basic features of the research articles that were included in this review and the second one portrays the frequent (top 5) contributing factors to medication errors, placed according to their type and significance. Study’s findings suggest that both individual and organizational factors are major determinants of medication errors. Conclusion: Medication errors by nurses are a type of patient malpractice, where the identification of contributing factors is vital. Since both categories of causality (individual and health system related) of medication errors contribute the same to their occurrence, consequently their address and resolution are of critical importance.