Código HTML:
<input type=button onclick="document.getElementById('fila1').style.display = 'none'" value="ocultar"><br> <input type=button onclick="document.getElementById('fila1').style.display = 'block'" value="mostrar"><br> <table border=1> <tr id="fila1"> <td>uno</td> <td>dos</td> </tr> <tr> <td>tres</td> <td>cuatro</td> </tr> </table>