Considering the existing conflicts about how an elevated body mass index (BMI) affects fertility, this study had the objective of evaluating the impact of overweight and obesity on the results of IVF/ICSI (in-vitro fertilisation/intracytoplasmatic sperm injection) performed at the Human Reproduction Centre of Faculdade de Medicina do ABC. Retrospective data from 208 IVF cycles of 191 women, performed at our laboratory from February through June, 2008, were used to calculate their BMI. On the basis of the results, the patients were divided into two groups: Group 1: BMI <25 kg/m² and Group 2: BMI ≥25 kg/m². Of the 208 cycles, 137 were from patients with BMI <25 kg/m² and 71 cycles from patients with BMI ≥25 kg/m². Patients' ages and the number of cycles with gonadotrophin-releasing hormone agonist and antagonist were similar in both groups. The doses of follicle-stimulating hormone used for ovarian induction per cycle, the number of retrieved oocytes, fertilisation rate, embryo quality and number of transferred and frozen embryos, the hyperstimulation, pregnancy rates, miscarriage rate and live birth rates showed no statistically significant differences. BMI does not appear to be a good parameter for the definition of IVF success. The association with other methodologies may produce more consistent data about body composition and its impact on fertility.