Thirteen boys with constitutional delayed puberty (CDP) were treated with a combination of short and long-acting testosterone esters (testosterone propionate, testosterone phenylpropionate, testosterone isocaproate). Mean age at the onset of treatment was 14.9 +/- 0.6 years and bone age delay was -2.7 +/- 0.9 years. The dose of testosterone used was 200 mg intramuscularly four times at three week intervals, and the treated CDP boys were followed for two years. All the boys with CDP entered puberty after the last dose (testicular volume > or = 4 ml), and growth rate increased from 4.5 +/- 0.5 cm/year, pretreatment, to 8.4 +/- 1.6 cm/year, posttreatment, at the two year follow-up. Height for bone age SD score did not change significantly from a mean of -1.1 before treatment to -1.3 after treatment, nor did predicted height before treatment (173.5 +/- 6.6 cm) and after treatment (173.3 +/- 4.9 cm). Combination of testosterone esters in a given dose and schedule is a safe and effective treatment for prepubertal boys with constitutional delayed puberty.