Yes and no, as it depends on circumstances.
- Did you get a good grade in their classes?
- Did you ask politely?
- Did you provide them with everything they need?
That last point is especially important. When I was a student, it was understood that when requesting a recommendation letter, you provided all the necessary documentation already filled out as much as possible, in an addressed, stamped envelope. As I got to a point where I was the one being asked for recommendations and dealing with students asking for them, it astonished me how this basic courtesy seemed to have faded.
That said, some things like med school applications have been moving online, but that's not the rule everywhere by any kind of margin as far as I know. Be polite, but make their jobs as easy as possible. I would also give them a copy of your CV and possibly a short 1 page personal statement to give them something to build a letter around.
But for goodness sake, please don't make the personal statement begin with the words "every since I was a child, I wanted to..." Or "when my grandmother got sick..." Because your professors have had it up to here reading those, believe me.