Thanks to the high counting statistics provided by a recent XMM-Newton observation of RX J1856.5Ϫ3754, we have discovered that this isolated neutron star pulsates at a period of 7.055 s. This confirms that RX J1856.5Ϫ3754 is similar in nature to the other six thermally emitting, nearby neutron stars discovered in soft X-rays with ROSAT.