A card-edge connector includes an insulative housing and a number of conductive contacts. The insulative housing defines a mating direction along a front-to-back direction and opposite front face and rear face. The insulative housing includes a pair of lengthwise walls, a central slot recessed from the front face along the front-to-back direction and at least one heat-radiating slot recessed from the front face along the front-to-back direction, and a number of contact-receiving passages in the lengthwise walls and communicating with the central slot. The heat-radiating slot is recessed from at least one of the pair of lengthwise walls and communicates with the contact-receiving passages along the mating direction. The conductive contacts are received in the contact-receiving passages.