Background Brucellosis is endemic in Iraq; particularly in Northern parts. Several problems are encountered in diagnosing the disease depending on serological tests; especially among cases suspected to have reactivation of the disease. Aim to evaluate the value of 2-Mercaptoethanol (2ME) test in diagnosing recurrent active brucellosis. Patients and Methods The study population consisted of 466 patients who had been treated and cured from a previous attack of brucellosis (diagnosed clinically or serologically), who returned suffering from symptoms suggesting a new attack of brucellosis with positive slide agglutination (SAT) test and on whom a 2ME test was conducted. Patients were collected from Al-Salam teaching hospital in Mosul during 2 years period (1999-2000). Results The 2ME test was positive in 184/408 (45%). The probability of having a positive 2ME test increased if the SAT was positive at high titers. The study also revealed high IgG antibody titers, mainly ranged between 1:160 and 1:640, with doubled positive rate among females in comparison to males. Conclusions The study revealed that 2ME test is useful in diagnosing about 45% of suspected cases with activation of previously treated and cured brucellosis. A direct SAT should first be conducted for suspected cases and the probability of having a positive 2ME test has increased if the primary SAT was positive at higher titers.