Investigations on the chromosomal inversion polymorphism were conducted on a Korean (Taenung) natural population of D. melanogaster during the period 1978 to 1992. A total of 66 different endemic and cosmopolitan inversions were found on both major chromosome pairs II and III. Some of them proved to be rare cosmopolitan types (2LKA, 2LNS, 2LF, 2RCy, 3LM, 3RKI, and 3RK), while others were endemics. The distribution of breakpoints for endemic and rare cosmopolitan inversions are not random along the two autosome arms. With respect to frequency changes, the 15-year survey revealed that five of the cosmopolitan types (2Lt, 2RNS, 3LP, 3RC, and 3RMo) exhibit cyclical frequency changes, whereas gene arrangement 3RP shows relatively stable frequencies. Tests for correlations between gene arrangement frequencies and several climatic variables gave no clear evidence for such relationships. Only one correlation coefficient out of 64 was statistically significant.