The problem of measuring bubble size distribution in liquid-gas foams is discussed. Results of some bubble size measurements are presented, and an attempt is made to relate the bubble size information to the rheological properties of the foam. A preliminary investigation of the effect on the bubble size distribution of passing the foam through a pipe is presented. Definite effects are seen, and further work is planned in this area. A method of measuring bubble size distribution continuously in a small region of a flowing foam would be of considerable use. Various ways of doing this are being investigated.