Two feeding trials were conducted to study the effects of calcium, phosphorus, and energy on the incidence of weak legs in broilers grown to 8 weeks of age. Chicks with a stilted gait and those reluctant to move or refusing to walk were considered to have weak legs. Trial 1 consisted of three treatments in which chicks were fed corn-soybean meal-based diets containing different levels (Treatment 1 < 2 < 3) of available phosphorous (aP) and calcium (Ca). No differences occurred in body weights and feed efficiency through 6 weeks. During the 6 to 8-week period, chicks in Treatment 1 gained less (P < .05) than chicks in Treatments 2 and 3. Percentage bone ash and circumference of the middle of the bone shaft were not different among treatments. Normal chicks had longer (P < .05) bones than chicks with weak legs. Chicks with weak legs had greater bone volume (P < .05) and a higher percentage of crooked bones (P < .50) than normal chicks. A deficiency of aP and Ca was not the cause of the weak legs in these heavy male broilers.Trial 2 consisted of three treatments in which chicks were fed diets containing varying levels of metabolizable energy (ME)/kg during the starting and growing periods. Body weight and feed efficiency were unaffected by any treatment during any period of the trial. The number of chicks with weak legs at 8 weeks was unaffected by diet. Chicks with weak legs had a greater bone volume (P < .06) and a higher percentage of crooked bones (P < .05) than normal chicks.