Describes three test high-rise buildings and the pressure measurements made on buildings. Gives results of internal to external pressure differences against height within building both with and without the ventilation systems in operation, compared with theoretical predictions. Discusses pattern of pressure differences. Suggests feasibility of pressurizing ground floor to reduce stack effect. NOTE Futher measurements of wind on two of these three buildings are given in 'Pressure differences caused by wind on two tall buildings' Tamura G.T. Wilson. A.G. ASHRAE trans. 74 no 2 p170-181.