If Statement

For some reason I cannot get an IF statement to work in PostGreSQL, even
though I am doing it in the format the manual tells me to...
Here is my query...

IF 1 = 1 THEN
    update contacts set deleted = TRUE
END IF;

I get the error ERROR:  syntax error at or near "IF" at character 1

I am using EMS's PostGreSQL Manager for windows.

Thanks