Theories of life-history evolution and (deleterious) mutation accumulation are central in evolutionary biology as they provide explanations to diverse array of biological phenomena. However, thus far these theories have been developed separately from each other. Empirical evidence suggest that these processes can no longer be looked in isolation from each other, because lowering the mutation rate is physiologically costly. Traits involved in lowering the mutation rate, such as germline repair and maintenance, trade-off against life-history functions, such as survival and reproduction. In turn, accumulation of mutations affect the vital rates. Hence, life-history traits and mutation rates co-evolve. This work brings together life-history and mutation accumulation theories by deriving a measure of invasion fitness that allows to characterise evolutionary stable life-histories and mutation rates simultaneously. This theoretical approach is illustrated with two specific life-history models: (i) a model with a trade-off between allocating resources to survival, reproduction and germline repair and (ii) a model with a trade-off between allocating resources to growth, reproduction and germline repair. I will also discuss the relevance of applying this work in understanding the evolution of ageing.