AM 382 4to is the sole witness to the text of the B-version of Þorláks saga helga. The first recto page of this manuscript contains a Latin poem about St Þorlákr. This poem has previously been printed three times, but in every case the text was less than adequate. This article publishes a newly-edited Latin text of the poem, as well as an English translation and detailed analysis of the poem and its connection with the B-redaction of Þorláks saga helga. The authors address, moreover, the relationship between the Latin Vita S. Thorlaci and the vernacular saga. Finally, they present evidence to suggest that Bergr Sokkason was the redactor of AM 382 4to.