Childhood obesity is a health hazard increasing worldwide. Preschool period which is under supervision of parents is a critical period to detect overweight and take precautions. We studied the factors affecting parental estimation of their preschool child's weight. Three hundred sixty seven mothers completed questionnaires consisting of child's and parents' anthropometric measurements, parents' assessment of their child's and their own weight status, and general information about their lifestyle. Mothers also chose their wish for current and future body image of their child from child drawings representing percentiles. Child body mass index-for-age z score (BAZ) was related to birth weight and child's appetite. BAZ was not related to child's gender, presence of chronic disease, family pattern, parental age, education or income. 43.1 % of mothers correctly assessed child's BAZ verbally. Maternal verbal estimation was correlated with maternal visual estimation, paternal verbal estimation and child's BAZ. Mothers' wish for future figure of the child was not related to child's BAZ, but showed correlation with mothers' wish for current figure of the child. Mother's correct perception of her child's weight was found to be high, consistent with her spouse and related to child's BAZ.