The parents of 56 consecutive children with a diagnosis of asymptomatic lipoma of the conus medullaris underwent detailed neurosurgical consultation. The pros and cons of both prophylactic surgery and conservative treatment were carefully presented. Both options were offered, and the parents were free to choose the preferred management. A total of 32 children underwent surgical treatment, and 24 were conservatively treated. Afterward, all patients entered the same protocol of serial neurological and urological follow-up at the Centro Spina Bifida. The mean follow-up periods were 9.7 years in the surgical treatment group and 10.4 years in the conservative treatment group. RESULTS: Permanent surgical morbidity was 3.1% (1 patient). During follow-up, tethered cord syndrome occurred in 9.7% of the surgically treated patients (3 of 32 patients) and in 29.1% of the conservatively managed children (7 of 24 patients). This difference did not result in statistical significance, but a clear trend in favor of surgery emerged. Young age at surgery and a cord/sac ratio < 50% appeared to be determining factors in the prevention of subsequent tethered cord syndrome. CONCLUSIONS: The small size of this series does not provide enough statistical evidence that surgical treatment can really improve the natural history of asymptomatic lipomas of the conus medullaris. Nevertheless, surgery appears at least advisable since it reduces by 75% the odds of TCS (p = 0.067), which is quite close to statistical significance ¹⁾