The aim of this work is to prepare oral liquid formulation of the non-steroidal anti-inflammatory drug mefenamic acid with sustained release property using floating in situ gelling technique. Gellan gum and sodium alginate separately were used to form the gels. Results showed the release from gellan gum was slower than that from sodium alginate in concentration dependent manner; where the drug release decreased as the amount of the gelling agent increased. Results showed that increasing the concentration of gellan gum (0.25,0.5 and 1%w/v) caused a decrease in gelation time and floating lag time with floating duration for more than 8 hours and significant decrease (p