The cost effectiveness of quality control in bacteriology stipulated by regulators is not established. The authors evaluated 111 surveillance procedures applied to 54 different operations; 100 had been performed in the authors' lab between 1965 and 1980, 91 of which had been performed 50 times. Forty-six conformed to CLIA requirements (CLIA-P). Thirty-seven others were CLIA-P, which had been modified (CLIA-PM) by reducing frequency and extent because few or no deficiencies had been observed. Eight others were devised by the authors (HH-P). The number detecting deficiencies, the per cent, and the mean per cent of deficiencies detected were: CLIA-P, 31, 67%, 3.5%; CLIA-PM, 8, 22%, 2.1%; HH-P, 8, 100%, 8.8%. Compliance with CLIA would cost HH $20,700/year (3.4% of total bacteriology laboratory cost). HH-P would cost an additional $9000/year. Discontinuation of CLIA-P not detecting deficiencies would reduce HH costs by $2900/year. Application of other low yield CLIA-P only to new lots of selected dehydrated media and fresh batches of selected reagents would reduce cost further by $2000/year.