Several P element insertion and deletion mutations near the 5' end of Drosophila melanogaster RpII215 have been examined by nucleotide sequencing. Two different sites of P element insertion, approximately 90 nucleotides apart, have been detected in this region of the gene. Therefore, including an additional site of P element insertion within the coding region, there are at least three distinct sites of P element insertion at RpII215. Both 5' sites are within a noncoding portion of transcribed sequences. The sequences of four revertants of one P element insertion mutation (D50) indicate that the P element is either precisely deleted or internally deleted to restore RpII215 activity. Partial internal deletions of the P element result in different RpII215 activity levels, which appear to depend on the specific sequences that remain after excision.