The reinforcement by crack deflection in boron carbide laminar composites is obtained by both controlling macrostructure and microstructure. This structure had never been studied before in boron carbide materials. Composites were prepared using tape-casting technique. Different composites with either porous interlayers obtained by pore forming agent, or weak interlayers obtained without adding sintering aid, or weak interlayers obtained by a mixture of boron carbide and boron nitride, or weak graphite or boron nitride interfaces have been elaborated and characterized. Reinforcement by crack deflection was observed in most of these composites. In comparison to the work of rupture of the dense material, i.e. 23.09 kJ.m⁻³, the following values were obtained for the laminar composites: 38 kJ.m⁻³ for composites with interlayers with corn starch (55 vol.%), 40 kJ.m⁻³ for composites with B₄C-BN interlayers, 30 kJ.m⁻³ for composites with weak interlayers in BN and 39 kJ.m⁻³ for composites with weak interlayers in graphite.