Dopamine plays a major role in the regulation of appetite and growth hormone. Dopaminergic agonists suppress appetite and dopamine D2 receptor antagonists enhance it. We examined the hypothesis that allelic variants of the DRD2 locus may be associated with weight and height. Sarkar and Sommer described two DRD2 polymorphisms that could be haplotyped by PCR. For weight, the mean Z score (National Center for Health Statistics) for 208 subjects without haplotype 4 was 0.086 versus 0.557 for 280 subjects with haplotype 4, P = 0.0003. Two separate sets of subjects were studied and these results were significant for both, providing an internal replication. For height, the mean Z score for 164 subjects without haplotype 4 was 0.1677 versus 0.6885 for 219 subjects with haplotype 4, P < 0.00001. These and other data suggest that the 4 haplotype is in linkage disequilibrium with allelic variants of the DRD2 gene that play a major role in the regulation of weight (obesity) and height, and may serve as a risk factor in late-onset non-insulin-dependent diabetes mellitus (NIDDM).