In a comparison of the reverse passive haemagglutination test (RPHA) with the direct immunofluorescent and rapid carbohydrate utilisation tests for the identification of Neisseria gonorrhoeae isolated from clinical specimens, 315 isolates of oxidase-positive Gram-negative diplococci were tested as pure 24-hour-old subcultures and samples from 108 similar organisms were taken directly from primary isolation plates. A similar test system was used to detect penicillinase production. Results showed agreement in 97.8% of organisms tested with the RPHA and conventional methods for identification of N. gonorrhoeae; similarly there was good agreement with conventional methods for detection of penicillinase production. The test was reliable and could be read within four hours; a result was therefore available on the same day the clinical specimen was received. The time and work involved in identifying N. gonorrhoeae using the RPHA was less than with conventional methods, but differentiation between N. gonorrhoeae and other Neisseria species from throat swabs proved difficult.