A valve for adjusting the air flow rate in an internal combustion engine; the valve presents: a valve body; a cylindrical tubular pipe obtained within the valve body and in which an air introduction channel is defined; a valve seat obtained along the air introduction channel of the tubular pipe; an actuation system; a shutter, mobile under the bias of the actuation system; and a connection flange, which is integral with a first end of the tubular pipe and presents a plurality of through holes which are crossed in use by corresponding fastening screws for rigidly fixing the valve body; the connection flange is provided with a lower plate and an upper plate, which are reciprocally parallel, facing and distanced and are arranged radially with respect to the cylindrical tubular pipe, and a number of ribs, which reciprocally connect the plates, are arranged perpendicularly to the plates, and are arranged axially with respect to the cylindrical tubular pipe.