The seasonal variations of caulerpenyne (CYN) levels, secondary metabolite of Caulerpa genus, were investigated in the fronds and stolons of Caulerpa taxifolia var. distichophylla recently present at three stations in the Gulf of Iskenderun, the Eastern Mediterranean Sea, including its relationships with various physicochemical parameters of the sea water. The CYN levels were highest in the spring, and decreased in autumn. Also, the CYN contents in the fronds were statistically higher than the stolons (p<0.05). The highest seasonal mean CYN content was determined in the fronds as 0.82 +/- 0.3 parts per thousand wet weight during summer season. However, there were no statistically significant differences in the CYN levels among sampling stations (p<0.05). It was also determined that the CYN levels had positive correlations with temperature and oPO4-P concentrations.