The present work presents a steady state two-dimensional theoretical analysis of laminar film condensation heat-transfer inside the condenser section of inclined wickless heat pipes flat-plate solar collector. A theoretical relation for the laminar film condensation heat-transfer coefficient is deduced and compared with the previous work. The comparison indicates good agreement between the: present relation and most of the experimental results previously published. The present relation is preferred to the previously published empirical and theoretical relations. This is because it is valid for wide ranges of the wickless heat pipes inclination angles and the condenser section dimensions ratio.