Objective: To determine whether nutritional status, anaemia and geohelminth infections were related to school achievement and attendance in Jamaican children. Design: A cross-sectional study using a randomly selected sample. Subjects: Eight hundred children aged 9±13 y randomly selected from those enrolled in grade 5 in 16 primary schools in rural Jamaica. Results: The mean height-for-age of the children was 70.37 z-score AE 1.0 s.d. with 4.9% having heights-for-agè 72 s.d. of the NCHS references. Anaemia (Hb`11 g/dl) was present in 14.7% of the children, 38.3% were infected with Trichuris trichiura and 19.4% with Ascaris lumbricoides. Achievement levels on the Wide Range Achievement Test were low, with children performing at grade 3 level. In multilevel analyses, controlling for socioeconomic status, children with Trichuris infections had lower achievement levels than uninfected children in spelling, reading and arithmetic (P`0.05). Children with Ascaris infections had lower scores in spelling and reading (P`0.05) Height-for-age (P`0.01) was positively associated with performance in arithmetic. Ascaris infection (P`0.001) and anaemia (P`0.01) predicted poorer school attendance. Conclusion: Despite mild levels, undernutrition and geohelminth infections were associated with achievement, suggesting that efforts to increase school achievement levels in developing countries should include strategies to improve the health and nutritional status of children Sponsorship: Funding was provided by the Commonwealth Caribbean Medical Research Council and the InterAmerican Development Bank.