Make sure you don't have the X (longitude) and Y (Latitude) reversed, and the Latitude longitude as negative if in the western hemisphere. Also, deicmal degrees work best.
edit: and if you are reading them in as an event theme, make sure to specify the WGS 84 as the coordinate system in the wizard.
edit2: Melita Kennedy Thanks for the catch....yaaa...I know better....just a typo, but fixed now. I'll blame it on my keyboard having issues today with cut-n-paste.