This paper investigates, with the help of computer-vision technology,the similarities and differences in the rhythm of themovements of the head in sentences in Finnish (FinSL) andSwedish Sign Language (SSL). The results show that themovement of the head in the two languages is often very similar:in both languages, the instances when the movement of thehead changes direction were distributed similarly with regardto clause-boundaries, and the contours of the roll (tilting-like)motion of the head during the sentences were similar. Concerningdifferences, direction changes were found to be usedmore effectively in the marking of clause-boundaries in FinSL,and in SSL the head moved nearly twice as fast as in FinSL. However, the small amount of data means that the results canbe considered to be only preliminary. The paper indicates theroll angle of the head as a domain for further work on head related rhythm.