Human Chlamydia infections have diverse clinical presentations and various biological methods are used for their diagnosis. Despite progress in laboratory techniques, theses methods are relatively slow: inoculation of chick embryos requires 4 to 12 days, cell culture from 2 to 3 days and indirect immunofluorescence a whole morning. Counter immunoelectrophoresis seems to have a future, as it is rapid (45 minutes), easy to perform, highly sensitive and applicable to routine examinations.