Against the background of the increasing incidence of many immune mediated childhood conditions, this study aimed to identify recent time trends and ethnic patterns of childhood nephrotic syndrome. A population-based cohort of children (0-15 years) diagnosed according to strict criteria with nephrotic syndrome (NS) was ascertained within the northern UK region of Yorkshire between 1987 and 1998. South Asian ethnicity was assigned based on the child's full name using a dedicated computer algorithm and expert individual checks. NS was diagnosed in 194 children, 170 (88%) of whom were steroid sensitive. The incidence of steroid sensitive NS was 2.0/100,000 pyrs (95% CI 1.7-2.3), peaking in 1-4 year olds (4.1/100,000 pyrs). Over the 12-year study period incidence rates of steroid sensitive NS were fairly stable although south Asian children displayed significantly higher rates than non-south Asians (P<0.01). The size of our population-based series reflects the relative rarity of paediatric nephrotic syndrome but is nonetheless recent and includes larger numbers than previous reports. The absence of any increase in incidence over the last decade contrasts with other paediatric immune mediated conditions such as asthma and diabetes.