Seasonal changes in free arginine concentration in Pinus radiata buds were studied in four clones from May, 1974 to June, 1975. The buds were from the tips of first order branches which had flowered the previous year, and the significant findings were as follows: (1) In general, arginine concentration in the buds of the four clones showed the highest peaks from December to March, a period spanning the time of flower initiation, and the lowest levels in Angust and September. (2) The timing of individual arginine peaks during the period of flower initiation matched roughly the timing of initiation of several female cone clusters, as determined from Clone 7 which characteristically initiates three cycles of female cones on its leading shoot. (3) The heavy-flowering clones showed higher arginine concentration than ther poorer flowering ones, especially at the time of flower initiation.