Sir—Selective serotonin reuptake inhibitors (SSRIs), alone or in combination with different psychotherapies and/or nutritional counselling, have been proved to reduce binge eating and vomiting frequencies in patients with bulimia nervosa (BN). However, percent reductions in bingeing and purging range from 18 to 87%.1 It has been suggested that the initial capacity, affinity or genotype of proteins involved in the regulation of SSRI action could account for differences in treatment outcome.2 The 5-HT transporter (5-HTT) represents the prime target of SSRIs, and a long (L) and a short (S) variant of the promoter region of the 5-HTT gene, with different transcriptional efficiencies, have been identified.3 The S allele of the 5-HTT gene-linked polymorphic region (5-HTTLPR) has been associated with poorer SSRI response in major depression.2, 4, 5, 6, 7