Experimental analysis of drinking in humans has yielded inconsistent results, ranging from no deficits relative to young groups, to substantial deficits. It is possible that cognitive or other factors can account for some of these differences between studies. Age-related dehydration in at-risk human populations may be minimized by ensuring adequate food intake and meal-associated drinking and/or provision of foods with high fluid content. With the exception of hypotension-related stimuli, age-related declines in drinking by rats after about 25% of the life span are small. Increased drinking at younger ages (3–4 mo) seems to be the unexplained anomaly; a generic explanation would be maturation in late adolescence of an as-yet unrecognized inhibitory mechanism.