We describe four isolates of Ng from men who have sex with men (MSM) patients that were able to grow in the abscense of CO2, as previously was described for N. gonorrhoeae ssp. kochii. These isolates were able to grow aerobically (without any added CO2) at 37 degrees C giving small colonies after 48 hs; two of them isolated from pharynx and urethra of one patient, were also able to grow without the blood supplement in the same conditions. In these unusual isolates the major outer-membrane proteins are of the same molecular weight than Ng. These isolates could be taken for other members of the genus if not confirmed by means of these (or other) methods.