This paper presents the results of a study where the effects of introducing code reviews in an organisational unit have been evaluated. The study was performed in an ongoing commercial project, mainly through interviews with developers and an experiment where the effects of introducing code reviews were measured. Two different checklist based review methods have been evaluated. The objectives of the study are to analyse the effects of introducing code reviews in the organisational unit, and to compare the two methods. The results indicate that many of the faults that normally are found in later test phases or operation are instead found in code reviews, but no difference could be found between the two methods. The results of the study are considered positive, and the organisational unit has continued to work with code reviews.