Objective. To determine whether parental errors in dosing liquid medication ca Design. Randomized convenience sample stratified to three study groups. Setting. General pediatric clinic, largely indigent and Latino. Patients. A total of 45 English-speaking and 45 Spanish-speaking children diagnosed with otitis media and treated with an antibiotic suspension. Intervention. Group 1 patients received the prescription and verbal instructions. Group 2 patients received the prescription and a syringe, then the correct dose was demonstrated. Group 3 patients received the prescription, a syringe with a line marked at the correct dose, and a demonstration. After returning from the pharmacy, parents administered the medication under observation. Parents in group 1 used a dispensing device similar to that planned for home use. The other groups used the syringe. After observation but before discharge, everyone received a syringe with a line marked at the correct dose. Patients were seen again at similar to 1 month, and parents demonstrated how much medication they had administered. Main Outcome Measure. Percent of parents who administered the correct dose. Results. Patients in group 1 received between 32% and 147% of the correct dose, with only 11 of 30 (37%) receiving the correct dose (+/-0.2 mL). In group 2, 25 of 30 (83%) parents administered the correct dose, and in group 3, 30 of 30 (100%) gave the correct dose. Simultaneous logistic regression indicated that accuracy of dosage differed across instructional groups and language. At follow-up, 23 of 26 parents demonstrated the correct dose. Conclusion. Education can decrease medication dosing errors made by both Spanish-speaking and English-speaking parents. Effectiveness was also shown at follow-up.