Whole grains play an important role in regulating body weight. However, interventions aimed to increase whole grains consumption have had limited impact on body mass index for age z-score (BAZ) due to insufficient understanding of knowledge, attitudes and practices (KAP) toward whole grains. This survey aimed to evaluate whole grains KAP among schoolchildren, as well as to investigate the associations of whole grains KAP with BAZ among the schoolchildren in Negeri Sembilan, Malaysia. This cross-sectional survey was conducted among 380 schoolchildren aged 9-11 years, cluster sampled from six randomly selected schools. Data were collected through a validated self-administered guided questionnaire. Body weight and height were measured. A majority of the schoolchildren had normal body weight (56.6%), moderate whole grains knowledge (42.6%), as well as neutral attitudes (66.1%) and poor practices (58.9%) toward whole grains consumption. Significant positive associations were found between knowledge and attitudes (r = 0.337; p