To acquire more insight into the results of treatment versus the "natural" course of glomus tumors, we studied the clinical data of 108 patients, in 58 of whom the disease was hereditary. During a period of 32 years (1956 to 1988), 175 tumors were diagnosed: 52 glomus jugulotympanic tumors, 32 vagal body tumors, and 91 carotid body tumors. The results of radical surgical treatment were disappointing for tumors located at the skull base, ie, nonradical in 59% (n = 23) of the cases, but very good for the carotid body tumors, for which 96% (n = 68) radical excision was achieved. Moreover, surgery at the level of the skull base dramatically increased morbidity, since it frequently induced cranial nerve palsy. During the follow-up period (maximal observation time 32 years, mean 13.5 years) none of the patients died of residual or recurrent tumor or developed distant metastases, irrespective of the mode and outcome of treatment. When these results are combined with the results of pedigree analysis, a realistic approximation of the "natural" course of the disease for both hereditary and nonfamilial tumors can be made. The results raise the question of whether this natural behavior is really improved by intervention. We conclude that removal of carotid body tumors and solitary vagal body tumors should be considered in order to prevent future morbidity. However, for skull base and bilateral glomus tumors a more conservative monitored "wait and see" policy can be sensible and should be considered in any proposal for treatment of head and neck paragangliomas.(ABSTRACT TRUNCATED AT 250 WORDS)