Objectives This paper aimed to report the prevalence of drop-out from organised sports between the ages of 10 and 14 years, and to examine potential associated detriments to levels of body fat. Methods All data were drawn from waves 4-6 of the Longitudinal Study of Australian Children. Participants' sport participation was parent reported and body fat percentage was measured using bioelectrical impedance analysis. A total of 4159 participants had sports participation data at age 10 years (M=10.32 years, SD=4.68). Results From 3013 sport participants at age 10 years, 29.7% (n=894) had dropped out of sports at age 12 years. Of 2016 sport participants at age 12 years, 33.3% (n=705) had dropped out of sports by the age of 14 years. There were no differences in body fat percentage at any age according to differences in sport participation behaviours. Conclusions Based on a high prevalence, drop-out from organised extracurricular sports during childhood and adolescence may be an important public health behaviour to consider. A solution-oriented approach to dropout from organised sports is recommended, but more evidence as to potential health detriments is needed using high-quality research designs.