Compared to males, females are at a much greater likelihood of receiving a later diagnosis of autism, which impacts their opportunity to receive early support. To assist with early identification, this systematic literature review aimed to ascertain whether females differ from males in the early childhood signs of autism. The small number of heterogeneous studies made it difficult to draw conclusions, although it appears that females and males under 6 years of age are more similar than different in terms of their expression of autistic behaviours. Given the discrepant sex/gender ratio in autism, these findings highlight the importance of exploring whether there are different and/or specific, not yet identified, early signs of autism in females and males.