This research aims at identifying the values of differences between the different weight statuses with significance of the value of the Body Mass Index (BMI) in the fitness level of the (9-12) years-old children. The preliminary measurements which represent the measurements of height and weight were conducted on a random sample consisted of elementary stage students from Al-Baha region whose age ranged between (9-12) years-old, and their characteristics were as follows: age (10.61 ± 0.89), weight (35.85 ± 12.41), height (140.51 ± 9.57), BMI (17.84 ± 4.64). The research methodology depended on identifying the relative distribution for the weight statuses of the research. The students were distributed according to the percentile distribution into four different weight statuses which included: underweight, healthy-weight, at risk of overweight, and overweight. A group of physical tests then have been applied on the following physical abilities (fixed maximum strength, transition speed, muscular endurance, muscular ability, flexibility, endurance, agility, compatibility, and balance), also the fitness level was calculated by the total of obtained (t) value by each student regarding the physical abilities of the research, and to calculate the differences between the groups, the one-way analysis of variance (ANOVA) test was used where the findings showed that there were significant differences between the different weight statuses in most of the results of the physical tests in favor to the children with healthy weight. The results also showed significant differences between the different weight statuses in the fitness level in favor to the children with healthy weight in most of the physical abilities, while the results of the effect's extent showed that the variable of ‘balance' was the most affected by BMI while the maximum strength was the last ranking in the list of physical abilities according to the effect's extent.