The present invention relates to recombinant adenoviral vectors based on adenoviruses that encounter pre-existing immunity in a minority of the human population and which harbor a chimeric capsid. The chimeric capsid comprises fiber proteins that have at least the knob domain of a human adenovirus that binds to the Coxsackievirus and Adenovirus Receptor (CAR) and a hexon protein from an adenovirus serotype that encounters pre-existing immunity in a low percentage of the human population.