BACKGROUND Hemangiomas, one of the most common childhood neoplasms, exhibit a characteristic history of rapid proliferation and slow spontaneous involution. Most of hemangiomas are often managed conversatively, requiring numerous years for spontaneous involution. However hemangiomas can threaten function in 10% to 20% of cases, less than 1% are truly life threatening. All these serious hemangiomas require treatment to avoid severe sequelae and in some rare cases to save the infant's life. OBJECTIVE To evaluate the efficacy, side effects, and influencing factors of intralesional triamcinolone in enhancing regression of various sizes and locations of hemangiomas and to discuss the optimal time and interval of the treatment. METHODS The retrospective study was done on 160 pediatric patients with hemangiomas, treated with intralesional triamcinolone injection at age 1 month to 15 years by the author at Queen Sirikit National Institute of Child Health from March 1995 to March 2008. Data were collected from interviews, examinations, medical records, photographs and telephone conversations. Standard statistical methods were used for comparison. The hemangioma sizes were classified into small (> 0-3 cm), medium (> 3-6 cm) and large (> 6-9 cm). Indications for the treatment were rapidly growing lesions, lesions with visual problems, bleeding, ulceration and cosmetic concern. Intralesional injection of triamcinolone was given in a dose of 1 to 2 mg/kg of body weight (maximum of 60 mg). The interval between the treatments varied from 4 to 12 weeks. Most patients were followed up at monthly interval at least 14 months through clinic visits. Mean follow-up was 3.6 years (range 14 months to 12 years). RESULTS One hundred and sixty patients, 111 girls and 49 boys were treated with this technique. The mean age at first injection was 16.1 months, with a range from 2 months to 9 years. The number of intralesional triamcinolone injection varied from single injection to twelve injections with a mean of 5.7 injections. The overall response rate was 90% (excellent at 70% and good at 20%). Maximum response was observed in children below the age of 1 year (excellent at 77.8% and good at 15.7%) and parotid hemangiomas (excellent at 93.1% and good at 6.9%). The difference between hemangiomas sizes and treatments interval result was not of statistical significance. CONCLUSIONS Intralesional administration of triamcinolone was devoid of systemic side effects and an effective initial modality for rapidly growing hemangiomas.