Abstract Let K be a nonabsolute field of characteristic p ≠ 2, G a locally finite group and KG its group algebra. Let ϕ: KG → KG denote the K-linear extension of an involution ϕ defined on G. In this article, we prove that if the subgroup 𝒰ϕ(KG), i.e., the ϕ-unitary units of KG, satisfies a group identity, then KG satisfies a polynomial identity. Moreover, in case the prime radical of KG is nilpotent, we characterize the groups G for which 𝒰ϕ(KG) satisfies a group identity. Key Words: Group identityGroup ringInvolutionUnitary units2000 Mathematics Subject Classification: 16U6016W1016S34 ACKNOWLEDGMENTS The second author is a "Postdoctoraal Onderzoeker van het Fonds voor Wetenschappelijk Onderzoek-Vlaanderen." Research partially supported by FAPEMIG of Brazil, the Fonds voor Wetenschappelijk Onderzoek-Vlaanderen, D.G.I. of Spain, and Fundación Séneca of Murcia.