We have studied the occurrence of the integration of non-T-DNA sequences in transgenic strawberry plants obtained through Agrobacterium inoculation. DNA from these plants was subjected to PCR amplification of the sequence of the gene trfA, which is located outside the T-DNA. The percentage of trfA-positive plants varied from 40% to 90%, with a mean of 65.7%. Backbone sequences were confirmed by Southern blot analysis.