A study was conducted examining the mutagenic effects of coal derived mild gasification products. Six gasification products derived from different coal sources and processing conditions were tested using the Ames Salmonella/microsomal assay following dissolution in dimethyl-sulfoxide (DMSO) or polyoxyethylene-sorbitan- monooleate (Tween-80). Previous analyses conducted on seven other gasification products demonstrated the importance of using at least two different solvents. In those analyses, one of the products was mutagenic using both solvents and one was mutagenic only using Tween- 80. In the current study each of the six samples tested positive in at least one analysis using DMSO or Tween-80, strains (TA-98) or (TA- 100), and with or without metabolic activation by S9 mix. Analysis of the mutagenic activity of basic, acidic, nonpolar, and polar neutral subfractions of five of the mutagenic and two of the nonmutagenic samples demonstrated that at least the nonpolar neutral fraction had mutagenic activity. The mutagenic activities of particular subfractions were attributed to their high concentrations of aromatic amines and other substituted aromatic hydrocarbons. This hypothesis was supported by the results of an experiment examining the relationship between the hydrogen/carbon ratio of the subfractions and their mutagenic effects.