Radiotherapy-induced lacrimal gland injury is a serious clinical problem currently lacking satisfactory therapeutic strategies. Exploring the mechanisms underlying secondary injuries caused by radiation may aid in the development of novel targeted medicine. In the current study, growth arrest and DNA damage-inducible 45 a (Gadd45a), a gene which is upregulated in irradiated skin, was observed as being overexpressed in the irradiated lacrimal gland. Moreover, overexpressed Gadd45a may impair lacrimal gland repair by inhibiting lacrimal gland epithelial cell migration and proliferation. Further signalling pathway analyses indicated that Gadd45a overexpression suppresses Akt (protein kinase B, PKB), P38 and JNK phosphorylation. Thus, the results of the current study suggested that Gadd45a may be a therapeutic target in radiation-induced lacrimal gland injury.