On the basis of 390 cases of lumbar spondylolysis found in 3132 competitive athletes, the authors introduce some judgements on the incidence of this illness in individual sports. The numerical analysis permits the authors to affirm that the incidence of this illness on competitive athletes is higher than the percentage reported in literature for the non-sports population. This statement assumes more relevance if one keeps in mind the high percentage of spondylolysis which has been observed in some sports disciplines such as diving (43.13%), wrestling (29.82%) and weight lifting (22.68%).