Objective To investigate the off-label prescriptions in pediatrics in West China Second University Hospital and to analyze the reasons and performance, so as to provide the baseline data for improving the rationality drug use in pediatrics in China. Methods The prescriptions of pediatrics outpatient department were randomly selected from May 2008 to April 2009; and the off-label use was analyzed according to the package inserts in the following aspects, the types of off-label use, the rate of off-label use in different age groups and categories of medicine. Results Of the total 2 400 prescriptions, 1 398 (58.25%) involving off-label use. All sample prescriptions contained 6028 records, 1 923 (31.90%) involving off-label use. The problems such as dosage (45.98%), frequency (21.17%) and age (18.19%) were the top-three types of off-label use. The rate in different age groups ranked as the top-three were school-age (61.56%), followed by preschool (60.77%) and infants (57.56). The top-five categories of medicines in off-label use were anti-allergy drugs (49.45%), digestive system drugs (49.32%), externally applied drugs (41.49%), Chinese patent drugs (34.60%) and nervous system drugs (33.78%). Conclusion The off-label drug use is widespread in pediatrics outpatient department. It is an effective approach to reduce off-label use and improve drug safety through strictly abiding by the instruction of usage and dosage as well as selecting a suitable dosage form.