A device for removably fitting carrycot seats and carrycots to baby carriages. Said carrycot seat or carrycot comprises a rigid, inverted-U handle, and the device is characterized in that each of the lower ends of this handle incorporates a mechanism for its direct anchoring in a respective attachment being laterally provided on the baby carriage, the handle having a control being apt to at the same time actuate the two anchoring mechanisms for simultaneously unlocking them. The control being provided to actuate said anchoring mechanisms comprises a rotatable cylinder having fixedly attached at each of two opposite points to its periphery a respective rope being connected to the respective anchoring mechanism, said cylinder and ropes being located in the hollow inside of the handle. The cylinder has an actuation appendage projecting through an opening being provided in the lower region of the central section of the handle.