Background. The objective of this study was to describe the incidence of childhood cancers in Brittany between 1991 and 2005, as well as its temporal and geographical variations. Methods. The incidence of childhood cancers was analyzed using data collected by the Brittany Childhood Cancer Registry. Crude incidence rates, age-standardized to the world population, and cumulative rates were estimated for all cancers and by diagnostic group at the regional level in Brittany. Standardized rates were also estimated for the four departments of Brittany. Poisson regressions were performed to estimate trends in annual incidence rates, to compare rates from the 2000–2005 period with those from the 1991–1999 period, and to compare incidence rates across departments. Results. Between 1991 and 2005, 1,176 cases of cancer among children under 15 years of age residing in Brittany were recorded by the registry. The age-standardized incidence rate for all cancers was 169.5 cases per million children per year. The most common cancers were leukemias (30%), central nervous system tumors (24%), lymphomas (12%), and neuroblastomas (8%). In Brittany, over the 1991–2005 period, one in 459 children was diagnosed with cancer before the age of 15. No significant upward trend was observed over the entire 1991–2005 period. Between the 1991–1999 and 2000–2005 periods, significant or borderline-significant increases in incidence were observed for lymphomas (RR: 1.38 [95% CI: 1.00–1.93]) and central nervous system tumors (RR: 1.24 [95% CI: 0.99–1.56]). A significant decrease in the incidence of renal tumors was observed (annual percentage change = -7.6%, p = 0.02) over the entire 1991–2005 period. No significant differences in incidence were observed among the four departments. Conclusion. The incidence of childhood cancers in Brittany is slightly higher than the national incidence. Although the observed increase in lymphomas and central nervous system tumors coincides with the growing use of medical information systems, we have no evidence to suggest that this increase in incidence is due to improved case registration.