I'm not sure why it's not working for you. All bitmaps I bring in have transparent backgrounds.
I'm assuming you are talking about a true 1bit black and white bitmap image. When you save the file and Place it what file format are you using. I always use TIFF. Otherwise you could try EPS with the transparent white option from Photoshop.
Also, have you tried importing it into any other application to see if it works ok in them InDesign etc?