The quantitative and qualitative chemical composition of a benzene extract from Rhodnius prolixus females at different nymphal state and at different reproductive ages were determined, using uni-and bi-dimensional NMR techniques.The chemical compounds present in the mixture were classified as A, B and C, according to their NMR chemical shifts.Compound A has signals in the range of δ 5.0 and 5.33 ppm,which is attributed to olefinic hidrogen and is found in all nymphal states and reproductive ages, therefore is not of utility as an age marker.Compoun C located between δ 2.5 and 3.5 could be attributed to hydrogen over nitrogen-bearing carbons, is very useful as an age marker to differentiate between the nymphal states and the beginning of the adult age.While compound B showing signalds between δ 4.0 and 5.0 ppm was identified as tri-acyglycerol, is and important marker to differentiate between non-ovipositor and ovipositor females, since this last age has none of this compound.It is also very useful to use the concentrations ratio of compound A relative to B, which is given by the ratio of their integrals, to establish the age difference of the nymphal states.We propose this technique to determine the nymphal states and the reproductive age of R. prolixus females, in a sample of triatomine collected at field conditions, which reveals an important information on the variables related to vector efficiency in Chagas disease.