A questionnaire survey for which there were 538 respondents from American clinical microbiology laboratories was used to assess the need for prolonged incubation of Septi-Chek blood culture bottles for the recovery of HACEK bacilli, Brucella species, Francisella tularensis, and nutritionally deficient streptococci from blood. Among a total of 219 reported isolates of these bacteria, in only 6 cases (2.7%) was incubation longer than 7 days required. Only 2 of 136 patients (1.5%) were noted to be bacteremic exclusively following incubation of Septi-Chek blood culture bottles for periods of greater than 7 days. It appeared from the results of this study, that incubation of Septi-Chek blood culture bottles for 7 days is usually sufficient in patients suspected of having bacteremia due to fastidious bacteria.