Abstract: This process is essentially characterized by enzymatic reactions which are carried out under anaerobic conditions between a liquid growth medium for mycoplasms containing a dilution medium of the sample of fluid to be analyzed and, on the one hand, a first substrate comprising dehydrated urea or glucose in the presence of a color pH indicator also in dehydrated form and, on the other hand, a second substrate comprising arginine also in dehydrated form or glucose in the presence of a color pH indicator and that the speed of the enzymatic response is followed while noting the time corresponding to the color change of the indicators, the respective quantities of urea and arginine or of glucose, on the one hand, and the concentration and the nutrient composition of the said growth and dilution medium, on the other hand, being first selected and standardized in such a way that for Ureaplasma urealyticum present at a supra or sub-pathological rate, the color change of the indicator is or is not obtained after a giv