Hepatitis C and brucellosis are infectious diseases that occur worldwide, and both are endemic in Egypt. Co-infection with both agents is possible, and this can involve the liver in various ways. In this study, we investigated serum tissue inhibitor metalloproteinase-1 (TIMP-1), viral load, and liver functions in patients co-infected with hepatitis C virus (HCV) before and after brucellosis treatment. Over 3 years, 241 consecutive HCV patients (before interferon therapy was received) with recurrent fever who had occupational contact with animals were tested for brucellosis co-infection by a standard tube agglutination test. In patients with dual infection, viraemia (RT-PCR), TIMP-1 measured by ELISA, and liver functions were assessed and re-evaluated 2 months after brucellosis treatment. The number of patients with HCV/brucellosis co-infection was 32 out of 241 (13.3%). TIMP-1, viraemia, AST, ALT and bilirubin showed significant decrease (improvement) after brucellosis treatment (p < 0.001) but an insignificant difference (p > 0.05) with regard to serum albumin and prothrombin concentration. The study revealed that brucellosis is an important infection in HCV-infected patients and can aggravate the course of disease, suggesting that early treatment and prevention are important.