Currently Being ModeratedSep 2, 2013 8:01 AM (in response to 46VR46)
That depends on which iMac you have. The pre-2006 models this forum covers do not have built-in SD card readers but can use external USB card readers.
Built-in SD card slots started with the Late 2009 iMacs.
This Apple article should help if you have a newer iMac:
Currently Being ModeratedSep 2, 2013 12:33 PM (in response to 46VR46)