In the present study, the gamma attenuation behaviours of the Titanium diboride (TiB2) reinforced boron carbide (B4C)-silicon carbide (SiC) composite materials were investigated against Co-60 gamma radioisotope source. In the experiments TiB2 unreinforced and 2% and 4% TiB2 (by volume) reinforced B4C-SiC composite materials were used. In the composite materials B4C/SiC ratio has been realized as 6/4 by volume. The linear and mass attenuation coefficients of the samples were carried out for Co-60 gamma radioisotope source which has two energy peaks (1.17 and 1.33 MeV). Then mass attenuation coefficients and half-value thicknesses (HVT) of the materials were calculated. Experimental mass attenuation coefficients were compared with the theoretical values which were calculated from XCOM computer code. Furthermore HVTs of the samples were evaluated and compared each other. It has been seen that the experimental and theoretical mass attenuation coefficients are closed to each other and differences are under 10 percent. In addition, TiB2 reinforced B4C-SiC composites have smaller HVTs than unreinforced one. Moreover 4% TiB2 reinforced B4C-SiC composite has smaller HVT than the 2% reinforced sample. Reinforcing TiB2 and increasing TiB2 ratio increase the gamma attenuation property of the B4C-SiC composites against Co-60 gamma radioisotope source.