should be payable by both landlord and tenant. Each paying a half of the monthly rental as the agents' fees. Of course, you can deal with agent as they have discretion to charge less!
peter21, do you mean in Hong Kong or in Shanghai? If the latter, no idea. If the former, fees are payable by both landlord and tenant, half a month's rental each. If it's a sale and purchase, the vendor and the purchaser both pay 1% of the sale price.