Background Humour is fundamentally a social phenomenon, occurring frequently in social and playful contexts. The positive affect resulting from an experience of enjoyed humour makes it socially rewarding. A lack of sense of humour has been associated with individuals with autism spectrum disorders (ASD), however, the existing literature is sparse and inconclusive. In this study, we investigated implicit and explicit humour understanding and appreciation in ASD. Method Specifically, an implicit item-item associative task was used, in which participants saw neutral-humorous and neutral-neutral sequences of two pictures in an encoding phase. Following a filler task, sequence recognition was measured in a yes/no test phase. At the end of the task, explicit measures of humour understanding and appreciation were completed by the participants, who rated the picture sequences for humour appreciation and funniness. Results Results revealed that, at an explicit level, participants with ASD were able to enjoy and understand the humorous stimuli as much as typically developing (TD) participants. At an implicit level, however, the results suggest that humour processing may be specially content-dependent in ASD. Fine-grained analysis on task performance indeed showed an altered humorous processing for social, but not for non-social humorous content in the ASD group, while that was not the case for the TD group. Conclusions These results suggest that participants with ASD may be distinctively motivated to attend to social reward cues such as social humorous stimuli. These findings are discussed within the social motivation hypothesis framework.