To study the cost-effectiveness of the histologic examination of tonsil and adenoid specimens, the histologic diagnoses for all routine (2,700) and nonroutine (71) tonsil and adenoid specimens during a 10-year period were reviewed. There were 27 routine cases (1%) and 56 nonroutine cases (79%) with a diagnosis other than normal, tonsillitis, or hyperplasia. Twelve of the 27 routine cases did not have a significant clinical history, and a potentially significant pathologic diagnosis was made in only 6 cases; in none of these cases did the pathologic diagnosis affect patient care. In all nonroutine cases, the pathologic diagnosis affected patient care. The average charge per case to detect potentially significant disease in routine and nonroutine cases was $64,718 and $525, respectively. We conclude that histologic examination of nonroutine cases is cost-effective, whereas in most routine cases with adequate clinical history, histologic examination is not cost-effective.