Complement C1q subcomponent subunit B (C1QB) is a crucial component of compliment C1Q which plays an important part in host defense system. The compliment C1Q components have been identified as biomarkers for the diagnosis of active tuberculosis. However, limited information is available about the expression of C1Q components in patients with HIV-TB coinfection and disease controls. The present study was aimed to determine the abundance of C1QB in serum exosomes of patients with HIV-TB coinfection, pulmonary TB, HIV mono-infection, and healthy humans. A total of twenty serum-derived exosome samples from patients with HIV-TB coinfection (n=5), pulmonary TB (n=5), HIV mono-infection (n=5), and healthy humans (n=5) were processed for the detection of C1QB using western blotting method. The beta-actin protein was used as an internal control to normalize the expression of C1QB between different samples of the study groups. The mean densitometric intensity values for C1QB of the study groups were compared using Mann-Whitney test and p-value < 0.05 was considered as statistically significant. The results demonstrate that C1QB was present in serum exosomes of all study participants. The mean densitometric band intensity for C1QB was statistically significantly higher in patients with HIV-TB coinfection (p-value: 0.003) and pulmonary TB (p-value: 0.015) as compared to healthy controls. However, the C1QB mean densitometric band intensity in exosome samples of patients with HIV-TB coinfection and pulmonary TB was found to be higher but the difference was not significant (p-value: >0.05) when compared to samples of HIV mono-infected patients. In conclusion, the present study reports increased expression of C1QB in serum exosomes of patients with HIV-TB coinfection and pulmonary TB as compared to HIV mono-infected patients and healthy humans and indicates that C1QB could be a potential adjunct biomarker to discriminate patients with HIV-TB coinfection and pulmonary TB from healthy humans. Further studies are required to establish the diagnostic potential and clinical relevance of altered C1QB expression in serum exosomes of patients with and without HIV-TB coinfection.