To assess the effectiveness of a nutrition and physical activity (PA) intervention on dietary intake (DI), nutritional knowledge (NK), blood pressure (BP), anthropometric measures and cardiorespiratory fitness (CRF) of schoolchildren.

Longitudinal study. DI, NK, BMI, waist-to-height ratio (WHtR), BP and CRF were all measured/calculated prior to (October 2014) and at the end of (June 2016) intervention delivery.

Two primary schools (one intervention and one control), Cork, Ireland.

Six-year-olds (n 49; mean age = 6·09 (sd 0·33) years) and 10-year-olds (n 52; mean age = 9·90 (sd 0·37) years).

There was a large and a moderate statistically significant difference between the change in systolic (P = 0·005, effect size (ES) = 0·165) and diastolic BP (P = 0·023, ES = 0·116), respectively, for 10-year-olds in the intervention and control groups. There was also a large statistically significant difference between the change in WHtR (P = 0·0005, ES = 0·386) and a moderate statistically significant difference between the change in NK (P = 0·027, ES = 0·107) for 10-year-olds in the intervention and control groups. There was a large statistically significant difference between the change in percentage of energy from protein in 10-year-old females (P = 0·021, ES = 0·276) in the intervention and control groups.

Project Spraoi is Ireland’s first ever school-based intervention that has been evaluated and proven effective in improving DI, NK, WHtR and BP in older primary-school children in one intervention school.