Objectives: To compare the flexural strength and the surface roughness of four composite resins (MF- Master Fill, Biodinâmica; CT- Concept and FM- Fill Magic, Vigodent; Filtek Z250, 3M ESPE), and to test the null hypothesis that there are not differences among these composites regarding the properties evaluated. Methods: Twenty specimens of each material were obtained according to the manufacturer's instructions and the ISO 4049. Ten specimens (stick shaped - 24 x 2 x 2 mm²) were submitted to, a flexural strength test of three-points bending (σ) and ten specimens(disc shaped - 7mm x 2 mm) were submitted to, a surface roughness evaluation, and the results are recorded as de mean roughness (Ra). The stick specimens were loaded to fracture in a universal testing machine (EMIC 2000) with crosshead speed of 1 mm/min. The Ra was evaluated in a profilometer (Surfcoder SE 1200). The σ and Ra results were statistically analyzed using ANOVA and Turkey test. Results: Means and standard deviations of σ (Mpa) and Ra (µm) were respectively: Z250 – 119,9 ±14,9 and 0,138±0,042; MF – 80,4±13,7 and 0,296±0,096; CT – 80,3±9,4 and 0,212±0,043; FM – 97,3±19,3 e 0,229±0,057. The σ average of Z250 was the highest compared to the other groups (p<0,05) that didn't show significant statistical differences among them. In relation to Ra, Z250 also showed the best results , followed by CT and FM, that didn't show differences between them, and MF that showed the biggest average of Ra. Conclusion: The micro-hybrid composite Z250 produced results of σ and Ra statistically better than the other materials tested denying the first null hypothesis.