Nine different types of plant material labeled with14CO2were used to compare two methods for analyzing14C in biological material. The methods were total carbon by wet oxidation (TC) and tissue solubilization using hyamine hydroxide (HH). In addition 3 sizes of material were used and 3 variations of the HH method were evaluated. Overall there were no significant differences between the HH and TC methods for14C activity, provided the samples are finely ground. Significant differences occurred in total counts and counting efficiency when the plant particle size decreased from .84 mm to .25 ram. Differences also were found between quench reducing treatments in the HH method. Differences between methods in terms of total counts, may be plant material specific