STUDY OBJECTIVE: To determine the prevalence of methylphenidate use among children in Iceland and show utilization trends from 1989 to 2006. Patterns of use were analyzed by sex, age and region of habitation, short-acting vs. long-acting formulations and presciber's specialty. MATERIALS AND METHODS: A descriptive observational study. Data was retrieved from the nationwide Register on Prescribed Drugs in Iceland and the Icelandic Directorate of Health surveillance system on prescribed methylphenidate. The study population encompassed the total pediatric population (0-18 year-olds) in Iceland during the study period. Total, sex-, age, and region-specific yearly prevalence rates were computed. Specific prevalence rates of short-acting and long-acting methylphenidate use were compared. Prescribed volume and number of prescriptions were analyzed in relation to specialty of prescriber. Prevalence ( per thousand) was defined as the number of children per 1,000 children in the population who received at least one methylphenidate prescription in the given year. RESULTS: The total prevalence of methylphenidate use among children (0-18) in Iceland was 0.2 per thousand in 1989 and 25.1 per thousand in 2006. Overall use was three times more common among boys than girls. Prevalence was highest at age 10, 77.4 per thousand among boys and 24.3 per thousand among girls. A variance in use between regions was detected. Prevalence of short-acting methylphenidate use decreased from 2003 (18.7 per thousand) to 2006 (6.8 per thousand), while prevalence of long-acting medication increased from 14.4 per thousand to 24.6 per thousand. In 2006 pediatricians were the most common prescribers of methylphenidate to children in Iceland, accounting for 41% of prescriptions. CONCLUSION: Use of methylphenidate among children in Iceland increased considerably from 1989 to 2004, when a plateau seems to have been reached. In accordance with the trend in many Western countries, a rise in use of long-acting drugs was detected concurrently with a steep decrease in use of short-acting drugs. Compared to utilization rates in Europe, prevalence of methylphenidate use among children in Iceland is high.