This study was conducted to determine the risk factors associated with the contamination of lettuce grown in the suburban area of Abidjan. A total of 216 samples were collected. Total aerobic bacterial counts and Enterobacteriaceae were investigated on soil, fertilizer, irrigation water and lettuce samples. Mean values of total aerobic count for sites 1 and 2 were 9.97 log 10 cfu/g and 8.20 log 10 cfu/g for the manure respectively, and 8.11 log 10 cfu/g for the soil of both sites. Lettuce samples from the market were more contaminated by Enterobacteriaceae than those obtained from the production sites. The main enterobacteria isolated were Salmonella gallinarum, Serratia marcescens and E. coli. All the lettuce samples analysed were contaminated by E. coli and Serratia. The prevalences of Serratia marcescens on lettuce from the market and from the production sites 1 and 2 were 58.33%, 33.33% and 41.67% respectively while those of E. coli were 33.33%, 25% and 8.33% respectively. The most common Salmonella serotypes isolated was Salmonella gallinarum with prevalences of 50%, 41.67%, 58.33%. Salmonella choleraesuis and Shigella sonnei were weakly represented. The manure has the highest potential as a source of contamination and infection of lettuce followed by the soils.