We have observed that using nitrocellulose in sample preparation for matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometry increases the yield of peptide [M+H]+ ions. Addition of nitrocellulose also provides improvement in sample-to-sample reproducibility of MALDI ion yield and improves the precision of peptide quantitation. Mass spectrometry and optical microscopy results suggest that the nitrocellulose modifies the crystallization of matrix/analyte solution to allow more even coverage over the sample surface.