Materials subjected to creep stress show a time-dependent formation and development of porosity accompanied by deformation. Especially in the tertiary creep stage, which ultimately leads to failure of the component both, porosity and deformation, increase rapidly. Using tomographic 3D in situ investigations, the porosity and deformation of a titanium-based metal matrix composite (MMC) reinforced by 15 % SiC particles were analyzed during the ongoing creep process. Defect analyses provide information on the quantity, geometry and spatial distribution of the formation and development of creep voids. The speckle pattern, required for digital volume correlation (DVC) to calculate displacements and from these deformations as well as the material strains, is intrinsically given by the particle reinforcement. Using DVC, the creep strains can be analysed and displayed spatially resolved. During creep, time-dependend changes of tensile and compressive strains were observed, which are related to porosity formation and development.  It was found that locally increased strains in the MMC material subsequently led to pore formation and growth. In the tertiary creep stage, necking occurred, leading to multidimensional strains. Tensile strains in the direction of mechanical loading led to void growth. Compressive strains occuring perpendicular to the loading direction prevented void growth and hence crack propagation.