Nearly all graduate programs require letters of recommendation. It's a fundamental part of the application process for virtually every graduate program, from master's degrees to doctoral programs and professional degrees (like law, medicine, or business). There are very few exceptions, and those would be exceptionally rare and usually noted explicitly in the program's application requirements.
Therefore, if you're applying to a graduate program, you should assume that you will need letters of recommendation and begin identifying potential recommenders well in advance of the application deadlines.