OBJECTIVES: This study examines associations between prenatal exposure to tobacco smoking and adverse behaviour in the offspring. METHODS: We included 1016 pregnant women from Greenland and Ukraine (526 from Greenland and 490 from Ukraine). Serum cotinine measurements were used to identify smoking pregnant women. When the children were from five to nine years of age, the parents assessed the child’s behaviour using the Strength and Difficulties Questionnaire (SDQ). RESULTS: Overall, smoking in pregnancy was not associated with a higher probability of adverse behaviour assessed by the total SDQ score. However, in the crude analysis smoking was associated with a higher mean difference of SDQ-total score. In Greenland the SDQ-total mean difference (MD) was (MD (95% CI)=1.31 points (0.42; 2.19)) and in Ukraine (MD (95% CI)=0.18 points (-1.2; 0.91)), whereas the adjusted mean differences were statistically non-significant. CONCLUSIONS: In utero exposure to tobacco smoking was not associated with a significant higher risk of adverse behaviour in the offspring, but elevated risk of adverse behaviour among children prenatally exposed to smoking cannot be excluded.