<DOCUMENT>
<TYPE>EX-21
<SEQUENCE>7
<FILENAME>a2106000zex-21.txt
<DESCRIPTION>EXHIBIT 21
<TEXT>
<Page>

                                                                      Exhibit 21


                                  SUBSIDIARIES
                                       OF
                         CABLEVISION SYSTEMS CORPORATION

<Table>
<Caption>

NAME                                                                      STATE OF ORGANIZATION

<S>                                                                       <C>
CSC Holdings, Inc.                                                        Delaware
Rainbow Media Holdings, Inc.                                              Delaware
Regional Programming Partners                                             New York
Regional MSG Holdings, LLC                                                Delaware
Madison Square Garden, L.P.                                               Delaware
Cablevision Electronics Investments, Inc. d/b/a The Wiz                   Delaware
Rainbow Regional Holdings, LLC                                            Delaware
RRH I, LLC                                                                Delaware
</Table>


                                  SUBSIDIARIES
                                       OF
                               CSC HOLDINGS, INC.

<Table>
<S>                                                                       <C>
Rainbow Media Holdings, Inc.                                              Delaware
Regional Programming Partners                                             New York
Regional MSG Holdings, LLC                                                Delaware
Madison Square Garden, L.P.                                               Delaware
Cablevision Electronics Investments, Inc. d/b/a The Wiz                   Delaware
Rainbow Regional Holdings, LLC                                            Delaware
RRH I, LLC                                                                Delaware
</Table>


</TEXT>
</DOCUMENT>