1. This study shows that the human cannabinoid receptors and their gene transcripts can be analyzed in blood samples when combined with polymerase chain reaction. The results also demonstrate that the expression of the cannabinoid receptors is dependent on gender and ethnic background. 2. Normal human volunteers who do not use marijuana have genes that encode for the marijuana (cannabinoid) receptor proteins. 3. Primer pairs from CB1 and CB2 cDNA coding region sequences showed identical amplified DNA band sizes in both DNA-PCR and reverse PCR, with human templates. This suggests that the CB1 and CB2 genes are intronless at least in their coding regions. 4. An advantage of the coding region being intronless may be that the expression of these genes will have one major RNA processing event to skip, thus making the conditions of their expression relatively quick and simple. This advantage may have implications related to the biological functions of these proteins. 5. We therefore concluded that the existence of human cannabinoid receptors and genes along with the discovery of endogenous cannabinoids (endocannabinoids) may be useful markers in elucidating the role(s) and mechanism(s) of action of cannabinoids.