The total H-1 and C-13 nmr spectral assignments of pyrrolizino[3,4,5-a,b]isoquinoline, benzo-[1,2]pyrrolizino[3,4,5-a,b]isoquinoline and 2-methylthiopyrrolizino[3,4,5-a,b]isoquinoline are reported. The concerted use of the COSY, HMQC, HMBC and nOe-difference experiments is used to generate total assignments of the H-1 and C-13 nmr spectra.