Of 432 patients referred for treatment of their cerebellopontine angle tumors, 53 with acoustic neuromas were managed initially without intervention but with adequate follow-up. Mean presenting tumor size in this subgroup of patients was 0.98 cm (range, 0.2 to 3.0 cm), and average growth rate was 0.16 cm per year. Twenty-one patients demonstrated tumor growth with a mean follow-up interval of 1.9 years. Of these 21 patients, 14 underwent microsurgical excision, 4 received radiation, 2 continued to be observed and 1 was lost to follow-up. The remaining 32 (60%) had no demonstrable growth with a mean follow-up of 2.13 years. Of these patients, 29 continue to be followed and 3 were lost to follow-up. Of the information evaluated, the only statistically significant relationship is with larger tumor size in elderly patients--most likely reflecting the propensity to opt for conservative treatment in elderly patients. Tumor growth rate was unrelated to presenting tumor size or patient age, which suggests that conservative treatment may be appropriate in selected patients.