1. Gunson's salivary chromosome preparations of Drosophila subobscura from widely separated sites in Scotland have been re-examined and inversions recorded according to the Mainx nomenclature.
2. Sixty-four diploid sets only were available. Of these, thirty-seven sets were found to be structurally homozygous on all chromosomes.
3. From Drumnadrochit in the north-central area of Scotland, the inversion found on the E-chromosome, so far as is known, has not previously been described. Its break-points have been noted, and the inversion is named E14.
4. A strain of D. subobscura from the small western island of Iona was the only one found to be completely homozygous in the five long arms of the chromosome set.
5. Samples of D. subobscura from two closely related localities in Midlothian, Scotland, also have been examined. Results are based on the analysis of 120 haploid sets in hybrids between the local race and the standard Küsnacht stock.
6. A slight difference in type and frequency of inversions has been noted between the two populations. The inversion E1+2 was recorded from Dalkeith, but was absent at Heriot, while U1, present at Heriot, was replaced by UST at Dalkeith.
7. The A-chromosome was structurally homozygous throughout.
8. Scottish samples of D. subobscura are characterized by their qualitative simplicity of polymorphism, the variety of inversion types being small. Chromosome orders analysed have been compared with those occurring in Western Europe and Israel.