The lipid bilayer thickness d(L) and the surface area A(L) in fluid lyotropic lamellar L-alpha phases of dipalmitoylphosphatidylcholine (DPPC) containing amphiphilic monohydrochiorides of [2-(alkyloxy)phenyl]-2-(1-piperidinyl)ethyl esters of carbamic acid (CnA, n=number of alkyloxy chain carbons) at DPPC:CnA = 1:1 and H2O:DPPC. 20:1 molar ratios have been estimated from small angle synchrotron X-ray diffractograms. CnAs intercalate between DPPC molecules, resulting in a lateral bilayer expansion and in a decrease of d(L). At the reduced temperature T-r=(T-T-c)/T-c=0.035, where T-c is the gel-fluid L-beta-L-alpha phase transition temperature, the values of d(L) (A(L)) equal to 3.289+/-0.012nm (1.060+/-0.012nm(2)), 3.391+/-0.011 nm (1.055+/-0.013 nm(2)), 3.403+/-0.013 nm (1.080+/-0.012 nm(2)), 3.418+/-0.012 nm (1.090+/-0.013 nm(2)), and 3.730+/-0.012 nm (1.025+/-0.012 nm(2)) were obtained for C5A, C7A, C9A, C10A, and C12A containing L-alpha phases, respectively. The increase of d(L) with increasing n is caused by the decrease in the difference in DPPC acyl and CnA alkyloxy chains lengths. The values of d(L)=3.733+/-0.011 nm and A(L)=0.902+/-0.012nm(2) obtained for C3A indicate that its location in the L-alpha phase is different from that of the other CnAs studied. The nonlinear dependencies of d(L) and A(L) on n can contribute to CnA's biological (local anesthetic, antimicrobial, antiphotosynthetic) effects that display similar dependencies on n.