Four strains of Campylobacter jejuni and four strains of Campylobacter coli were used to compare the quantitative growth of Campylobacter cells on blood agar base no. 2 (Oxoid), brucella agar (BBL Microbiology Systems and Difco Laboratories), campylobacter agar base (Difco), Columbia blood agar base (Difco and Oxoid), and Mueller-Hinton agar (Difco and Oxoid). Columbia blood agar base and blood agar base no. 2 were inhibitory to most of the strains tested, as evidenced by reduced (10- to 1,000-fold) colony counts compared with other basal media. One of the brucella agars was inhibitory to two of the C. coli strains. The inhibitory effect of these media could be eliminated by addition of FBP (0.05% each ferrous sulfate hydrate, sodium metabisulfite, and sodium pyruvate) or 7% defibrinated sheep blood. However, addition of FBP or blood to brucella agar, campylobacter agar base, or Mueller-Hinton agar did not significantly affect the count, indicating that supplements are not required in these media for growth of Campylobacter in pure culture.