A high level expression system for production of an immunoglobulin-binding protein, in Escherichia coli was studied. The protein, called protein L(I-IV) consists Of four immunoglobulin-binding domains of the native protein L, A simple fed-batch cultivation strategy was used to investigate the influence of different induction times on cell growth, viability, acetic acid formation and product formation. Induction allowing product formation for several hours, i.e., in this case in early exponential phase, was most favorable in terms of product yields. The highest specific yield obtained was 150 mg protein per gram cell dry weight (dw), corresponding to 360 mg per liter broth. The leakage of product into the media was less than 5%. Induction in early exponential phase lead to the highest amount of acetic acid, 1.47 g/g dw. Viability decreased significantly after induction.