Immunohistochemical staining of immunoglobulin‐containing plasma cells was performed on odontogenic keratocysts, dental (periapical) and dentigerous cysts. IgG‐containing plasma cells were the predominant species in all cyst types examined, with a much lower percentage of IgA‐ and few IgM‐containing plasma cells. Statistically significant differences in the percentage contributions of IgG and IgA plasma cells were observed between the keratocyst and both the dental (periapical) and dentigerous cysts and for IgM between the keratocyst and dental (periapical) cyst. Intense extracellular staining was observed for IgG in all cys