Background: According to high incidence of fever and its side effects in children and also because of different effects of drug regimens on reducing fever, we decided to investigate three kinds of adminstration of acetaminophen (aral with regular dosages, Rectal with regular and high dosages) on children whom were admitted in shaheed Beheshti Hospital in kashan in 2004.

Materials and Methods: This randomized clinical trial was performed among 120 patients aged 6 months to 6 years with fever (axillary temperature ³ 38 ^° c). Patients divided in 3 groups. Group A (40 patients) received oral acetaminophen with dose of 10-15 mg/kg acetaminophen. Group B and C received acetaminophen rectally with dose of 10-15 mg/kg and 30-60 mg/kg,respectively. Recovery was defined as reducing axillary temperature at least 1 ^° c.Data analysis was performed using Chi Square test.

Results: The frequency of recovery in groups A, B and C after 1 hour of adminstration of acetaminophen was 34 (85%), 32 (80%) and 36 (90%), respectively (p<0.05). It was 37 (92.5%), 38 (95%) and 39 (97/5%) after 3 hours (p<0.001) and 10 (25%), 14 (35%) and 22 (55%) after 6 hours (NS) of administration of acetaminophen in groups A, B and C, respectively

Conclusion: High dose rectal acetaminophen is much more effective in reducing fever of children in comparison of regular dose of acetaminophen, orally or rectally.