This paper describes the study and results from a small-scale lab rig, build to test different riser slug control strategies without the huge costs involved in larger scale experiments. Earlier experiments on this small-scale rig have shown that it was possible to stabilize the flow using a PI controller with a pressure measurement located upstream the riser base as measurement (Sivertsen and Skogestad, 2005). During these earlier experiments, the slug flow behaved a bit differently from that observed in larger facilities. Instead of severe slugs where the gas entered the riser, the gas was released as Taylor bubbles. As one Taylor bubble managed to enter the riser, several more would quickly follow as the pressure drop across the riser decreased. To get a slug flow pattern that was closer to severe slugs, the length of the riser and the size of the gas buffer tank were increased. After implementing this new equipment, the slug flow regime resembled more the severe slugs seen in larger rigs. The aim now was to control the flow using only topside measurements and to compare with results found using upstream measurements. A controllability analysis was performed in order to screen the different measurement candidates using a model developed by Storkaas et al. (2003). The analysis showed that it should be possible to control the flow using only topside measurements. The results from this analysis were then used as a background for the experiments performed in the lab. The experimental results were successful. They showed that it was possible to control the flow and the results were actually better than predicted from the analysis. in fact, the results are comparable with the results obtained when using a pressure measurement upstream the riser (subsea measurement). (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V All rights reserved.