The unit for supplying and inserting products (2) to and into container elements (3, 3A) advancing along a line of a packing machine (M) comprises a flat element (8) provided with a through-slit (10), and a disc (4) affording through-holes (6). The unit (1) is positionable with respect to the line of the packing machine (M) such that the slit (10) is arranged above the container elements (3, 3a). Products (2) are supplied onto the disc (4) which products (2) are to be inserted in the container elements (3, 3a), each through-hole (6) being of such a size as to be able to receive and house internally thereof a product (2). The disc (4) is mounted above the flat element (8) such that the products (2) housed in the through-holes (6) rest on the flat element (8). The disc (4) is also activatable in rotation with respect to the flat element (8), and with respect to the container elements (3, 3a) advancing long the line, in order to bring the products (2) received in the through-holes (6) above the slit (10), contemporaneously with a transit of the container elements (3, 3a) below the slit (10) such that the products (2) fall directly internally of the container elements (3, 3a).