The study was designed to assess the effect of humidity conditioning for various exposure periods on the quality of fingerprints developed with three chemical reagents: DFO, ninhydrin, and indanedione (the latter in two formulations). Paper exhibits of two types with "controlled" fingerprints were left for different periods of time in the ESDA humidifier, processed by ESDA, and finally treated with the aforementioned fingerprint reagents. Two types of paper were used: A4/80 g white printer paper (paper 1) and white writing paper with a blue grid of the kind often found in student notebooks (paper 2). The study found that the optimal conditions for ESDA detection of indented writing on documents can affect subsequent fingerprint development. Two of the three amino acid reagents, ninhydrin and indanedione, were found to be particularly sensitive to pre-exposure to high humidity. Although very short exposure improved the results, longer exposure (more than a few minutes) significantly reduced the quality of the developed prints. DFO, on the other hand, was found to be much less susceptible to previous humidifications; even 1 hour of exposure to high humidity did not affect fingerprint quality. This paper thus recommends DFO as the technique for fingerprint development on paper items that have been exposed to high humidity. 6 figures, 3 tables, and 12 references