The authors have proved Ostrowski type inequalities for functions whose derivatives satisfy some convexity conditions. The proofs of the results obtained are interesting and elegant. For a comprehensive list of results related to Ostrowski’s inequality one may see the book of S. S. Dragomir and Th. M. Rassias: “Ostrowski type inequalities and applications in numerical integration” (2002; Zbl 0992.26002), where several results and an extensive list of references are provided.