The olm (Proteus anguinus), with a predicted maximum lifespan of more than 100 years, is the longest-lived amphibian, which in addition possesses a range of unique adaptations to its dark, subterranean cave habitat. To assess the underlying molecular signatures, we present the first comprehensive transcriptome of the olm. Our study provides gene expression data across six organs and comparative genomics analyses, accessible via an interactive web server: http://comp-pheno.de/olm . The data uncover significant organ-specific gene expression, with the brain showing the highest number of organ-specific expressed genes. Our findings reveal significantly more genes under strong negative selection than positive selection, particularly in brain-specific expressed genes. Processes under positive selection in the olm resemble those in other long-lived species.