In the present paper, the author has obtained an improved version of an Opial-type inequality involving higher-order derivatives of two functions given by

*R. P. Agarwal* and

*P. Y. H. Pang* [Math. Nachr. 174, 5-20 (1995;

Zbl 0831.26007)]. Further, two inequalities which deal with the refinements of Opial-type inequalities given by

*R. P. Agarwal* and

*P. Y. H. Pang* [J. Math. Anal. Appl. 190, No. 2, 559-577 (1995;

Zbl 0831.26008)] are also given.