The primary objective of this paper is to report and discuss variations in AAGNPP of deserts. Specific objectives are related to a number of questions. What ecosystem types within and between deserts have the greatest variations in AAGNPP? Under what environmental conditions are highs and lows observed? Are factors other than water availability limiting ANPP in deserts? What is the probable contribution of belowground production to total annual net primary production (ANPP)? Before discussing these question, I will first attempt to precisely define what I mean by primary production. Then I will present a brief history of primary production studies in deserts, pointing out the recentness of such studies. I will also discuss the methodological difficulties in measuring ANPP in deserts, which largely explains the paucity of primary production studies in deserts.