Artificial Light At Night (ALAN), which dramatically expands worldwide, is considered as a threat to biodiversity. Thus, it is of particular interest to understand how ALAN may affect the day/night cycle gene expression, which could be one of the mechanisms contributing to the harmful physiological and behavioural effects of ALAN on animals. Amphibians, that is the animal group with the worst conservation status, are frequently found in urban and peri-urban wetlands, which are subjected to ALAN. We previously showed that ALAN reduced nocturnal activity and affected breeding behaviour and success of adult toads (““Bufo bufo”“). Here, we studied, for the first time, gene expression changes in response to ALAN in this species. We first assembled a ““de novo”” transcriptome of ““B. bufo”” tadpoles and then used Illumina RNA-seq to evaluate the transcriptome-wide gene expression response of ““B. bufo”“, experimentally exposed at night, to ecologically relevant light illuminances (control, 0.1 or 5 lux) and sampled at two times (day and night). ALAN affected the day/night cycle gene expression, by reducing the number of differentially expressed genes between day and night and by inducing a day/night cycle expression in non-cyclic genes in control conditions. ALAN also affected nocturnal gene expression, in a dose-dependent way, as the expression of 1194 and 3676 genes differed when comparing 0.1and 5 lux, respectively, with control. Moreover, those differentially expressed genes were mainly under-expressed with ALAN. Among the genes affected by ALAN, the majority were involved in immune response, which may affect tadpole’s growth and survival.