Problem: for children to have a good motor development, it is not enough that they play, exercise or play sports, since many other factors influence or determine development, and it is necessary to study them to objectively know the reality, the state and the needs of children, and based on this evidence, motor stimuli for children must be programmed. Objective: the Body Mass Index (BMI) was correlated with the result of the Complex Motor Test (CMT), which evaluates the coordination level, in schoolchildren. Methods and materials: descriptive correlational study, with a sample of 395 children from 3 schools in Medellin-Colombia, different in stratum and sports modality. The distribution of the sample was random and proportional, according to age and gender. Participants had their BMI taken and the CMT applied, a univariate analysis was performed and, according to the type of distribution, parametric or non-parametric tests were used. The instruments used were electronic scales, laser height rod and stopwatch. The schoolchildren filled out the informed consent and assent. Results: no correlation was found between BMI and CMT. The social stratum and the type of sports emphasis at the school did not show any correlation either. BMI is not directly related to the result of CMT, although progression with age is evident for males. In the female gender, the results in are low and do not improve significantly with age between 12 and 14.5 years. No relationship was found between the social stratum and the type of school for the CMT result. Conclusions: In order to contribute to the motor development of schoolchildren, an intervention aimed at improving the coordination level of schoolchildren should be programmed from the physical education class in the three educational institutions.