This is a case - control study aimed to clarify the possible role of IFN-ɣ +874 T/A gene polymorphism (single base change) in the first intron as predictive factor for tuberculosis infection and disease development. This study dealt with Iraq-Babylon Province population of ( 60) patients with culture & AFB, proven pulmonary tuberculosis and ( 20) healthy age and sex matched control persons. The genotyping was carried out by using Amplification Refractory Mutation System (ARMS- PCR) technique and the IFN- serum level was estimated by ELISA technique. Statistical analysis had revealed that individuals homozygous for the interferon -ɣ (+874) (A allele) were markedly overrepresented among the patients with tuberculosis, 28 (46.6%), as compared with apparently healthy control subjects, 3 (15%) and had a (4.958-fold) increased risk of developing tuberculosis than the other two genotypes (AT and TT), [p value = 0.012]. IFN- ɣ serum level was closely linked to the +874 T/A alleles as allele A homozygous patients (AA) produced lower levels of IFN- ɣ (mean = 456.2 pg/ml) when compared with patients carrying one or two copies of allele T (mean= 699.1pg/ml) and (mean=962.375 pg/ml) for AT and TT, respectively. It was found that the mean of IFN-ɣ serum level of control individuals was (442.431pg/ml) that approximately near to that recorded for the genotype (AA) and less than for (AT) and (TT) genotypes in patients.