The relative age effect (RAE) refers to that children born early in their year of birth show higher performance compared to children born late in the same cohort. The present study evaluated whether RAE exists within non-competitive physical education (PE) attainments, change in RAE magnitude with age, and possible gender differences. The results show a drop in PE attainment and a difference in number of high and low marks between the first and second half-year. Of the pupils who attained the highest mark, 73% were born in the first 6 months. In lower-secondary school, RAEs were larger in girls compared with boys. A possible explanation for the results is that the PE-teachers might be inspired by product-oriented criteria.