The paper mainly concerns the existence of a solution to a class of boundary value problems for coupled systems of nonlinear fractional differential equations. The article is very similar to the reference [X. Su
, Appl. Math. Lett. 22, No. 1, 64–69 (2009; Zbl 1163.34321
)]. The novelty is the condition on the boundary which introduces more difficulty in the analysis of the existence of solutions. In particular, the result is obtained by the Schauder fixed point theorem to an operator defined on a suitable function space.