OBJECTIVE To describe the success rate and the complications after procedures to diagnose abdominal non-Hodgkin's lymphoma in children and adolescents. METHODS A retrospective cross-sectional study was conducted with a population consisting of children and adolescents with abdominal non-Hodgkin's lymphoma diagnosed between September 1994 and December 2012. The sample comprised of 100 patients who underwent 113 diagnostic procedures, including urgent surgery (n=21), elective surgery (n=36), and non-surgical diagnosis (n=56). RESULTS The most frequent procedures were laparotomy (46.9%) and ultrasound-guided core biopsy (25.6%). The rate of diagnostic success was 95.2% for urgent surgeries; 100% for elective surgeries and 82.1% for non-surgical procedures (p<0.05). The rates of complication during the three diagnosis procedures considered were significant (p<0.001; 95.2% of the urgent surgeries, 83.8% of the elective surgeries, and 10.7% of the non-surgical procedures). The length of time before resuming a full diet and starting chemotherapy was significantly reduced for patients who underwent non-surgical procedures when compared with the other procedures (p<0.001). CONCLUSIONS Non-surgical procedures for the diagnosis of pediatric abdominal non-Hodgkin's lymphoma are an effective option with low morbidity rate, allowing an earlier resumption of a full diet and chemotherapy initiation. Furthermore, non-surgical procedures should also be considered for obtaining tumor samples from patients with extensive disease.