Abstract : Intelligence is defined as a general mental ability for reasoning, problem solving, and learning. To assess the intelligence quotient (IQ) of a child, many factors play a role such as genetics, family, social, cultural and environmental. Blood lead levels (BLLs) in 5 micrograms per deciliter (µg/dL) or more are associated with decreased intelligence, behavioral disorders and learning problems. This study aimed to determine the prevalence of low IQ and its associated factors. A cross-sectional study design was conducted in West Bangka. Data on 190 children aged 2-9 years and their mothers were collected. The subjects were divided into two categories on the results of intelligence assessment (IQ test) by Startford-Binet intelligence scale. Descriptive and binary logistic regression analyses were applied to determine the prevalence and associated factors with low IQ. The total prevalence of BLL > 5µg/dL and low IQ in children were 57.9% and 62.3%, respectively. However, after adjustment for head circumference for age, height for age, maternal and paternal education level, BLL was not associated with low IQ in children. Children with microcephaly were more likely to be low IQ (adjusted OR : 4.304 95% CI : 1.602 – 11.563, p = 0.004) than children with normocephaly. Children whose mothers had low education level were at a higher risk for low IQ (adjusted OR : 3.785, 95% CI : 1.976 – 7.248, p = 0.000) compared to children whose mothers had high level education.