Recent developments in the molecular biology of the prostanoid receptors has allowed the investigation of the physiological roles of each individual receptor type and subtype. The following article reports the prostanoid receptor distributions deduced from Northern blot and in situ hybridization analyses, summarizes the phenotypes of each receptor knockout mice, and discusses recent studies investigating the effects of each receptor deficiency on the inflammatory response and female reproductive processes. The combination of expression pattern and knockout analyses enabled us to determine which receptor expressed in a particular cell is important for the maintenance of normal and/or pathological physiology. The results from these analyses may be useful in the development of novel therapeutics that can selectively manipulate prostanoid-mediated actions.