This thesis contains six papers closely related to current research topics in the field of economic evaluation in health care. The thesis discusses methodological features of cost-effectiveness analysis (CEA) and cost-benefit analysis (CBA). It further relates to issues of modelling and how to account for uncertainty in economic evaluations. The thesis contributes both with an analysis of the costs and benefits of hormone replacement therapy (HRT) and new approaches for analysing uncertainty in economic evaluations. The first part of the thesis (Papers 1-4) analyses the costs and benefits of HRT in the prevention and treatment of postmenopausal women’s health problems. The second part of the thesis (Papers 5-6) analyses issues of uncertainty in economic evaluations. Contents: Paper 1: Willingness to Pay for Hormone Replacement Therapy. (A revised version of this paper has been published in Health Economics, Vol. 7 No. 1, 1998, pp 31-38.) Paper 2: The Impact of Hormone Replacement Therapy on Quality of Life and willingness to Pay. (Co-authored with Magnus Johannesson, Peter Henriksson and Roland T. Strand.) (This paper was published in British Journal of Obstetrics and Gynaecology, Vol. 104, 1997, pp 1191-1195.) Paper 3: Estimating Hip Fracture Costs and Potential Savings. (Co-authored with Ulf-G Gerdtham.) (This paper was published in International Journal of Technology Assessment in Health Care, Vol. 14, 1998, pp 255-267.) Paper 4: A Computer Model to Analyse the Cost-Effectiveness of Hormone Replacement Therapy (Co-authored with Magnus Johannesson and Bengt Jönsson.) (A revised version of this paper has been published in International Journal of Technology Assessment in Health Care, Vol. 15, No. 2, Spring 1999, pp 352-365.) Paper 5: Bootstrap Confidence Intervals for Cost-Effectiveness Ratios: Some Simulation Results. (Co-authored with Magnus Tambour.) (A revised version of this paper has been published in Health Economics, Vol. 7, No. 2, pp 143-147.) Paper 6: Non-Parametric Willingness to Pay Measures and Confidence Statements. (Co-authored with Magnus Tambour.) / <p>Diss. Stockholm : Handelshögsk.</p>