Background: Errors in the prescription and transcription of medications in pediatric services is a source of adverse events that can be prevented. Aim: To determine and compare the frequency of prescription and transcription errors for intravenous drugs in four pediatric services in a regional general hospital. Material and Methods: Cross sectional analysis of a probabilistic sample of 500 prescriptions of intravenous medications. Information was gathered using an instrument from the American Academy of Pediatrics. Results: The detected prescription errors were illegible indications in 20%, lack of dosing indication in 11%, omission of the administration route in 24% and omission of the frequency of administration in 15%. Transcription errors were illegible transcription in 3%, not transcribing all indicated medications in 4% and transcription of medications that were not prescribed in 3%. Twenty one percent of prescriptions and 6% of transcriptions had at least one incorrect action. In the different services studied there was a significant association between the percentage of incorrect prescriptions and transcriptions and between illegible prescriptions and transcriptions. Conclusions: A high percentage of errors in prescription of intravenous medications and their transcriptions, was detected in these services. A better quality of care control is required. (Rev Med Chile 2010; 138: 1524-1529).