The purpose of this study was to assess the changes in the foot dimensions in children and adolescents (3-18 years of age) from Krakow (Poland), between the years 2010 and 2020. The examined group of children and adolescents (3-18-year olds) took part in two cross-sectional surveys carried out in 2010 and 2020. The cohort examined in 2010 consisted of 1,989 females and 1,893 males and the 2020 series included 1,702 females and 1,584 males. Body height (B-v), length of the lower limbs (B-sy) foot length (pte-ap) and breadth (mtt-mtf) were measured. The last two measurements were the basis for calculating the foot index and estimated area of the foot. Generally, children examined in 2020 had relatively wider feet in proportion to their length compared to their peers from the 2010 cohort. This change was mirrored by secular trends regarding the estimated area of the foot. Additionally, a secular decrease of the length of the foot was compensated by the increasing width of this segment of the body, which among girls occurred especially after 10 years of age. The present study provides new information regarding secular changes in foot proportions among Polish children and adolescents. Results obtained in this stud are additionally significant, as there is no similar research concerning the population of Poland.