Urethral swabs for 75 males with urethritis were extracted into tryptose phosphate broth and then equal aliquots were dispensed into vials containing sucrose phosphate buffer (2SP) and urease color test medium (U-9). No antibiotics were present in the media. After transport to the laboratory, the recovery of C. trachomatis and Ureaplasma urealyticum was evaluated after inoculation into [human synovial] McCoy''s cell culture and agar medium, respectively. C. trachomatis was recovered from significantly more patients (17 vs. 12, P = 0.03) with higher inclusion counts (P < 0.01) in specimens transported in 2SP as compared with those in U-9 medium. No significant differences between the isolation rate of U. urealyticum and that of Mycoplasma hominis were found with the 2 media. The rate of inactivation of C. trachomatis and U. urealyticum at 4.degree. C was examined by means of reference strains. The inactivation of C. trachomatis was similar in 2SP and U-9 media, but the number of inclusions was consistently greater in the 2SP. In contrast, the number of colony-forming units of U. urealyticum actually increased over a 24 h period in both media. 2SP is apparently the best medium for the combined recovery of C. trachomatis and genital mycoplasma. The use of 1 transport medium and hence a single swab culture has the obvious advantages of saving time and expense for physician and laboratory, and for the patient it will eliminate the possible discomfort of having multiple cultures taken.