Lycopene produced by recombinant Escherichia coli was tested for subacute oral toxicity to determine its No-Observed-Adverse-Effect Level (NOAEL). Doses of 0, 200, 500 and 2000 mg/kg body weight/day were administered daily by gavage to 10 rats/sex/group for 28 days. No statistically significant, dose-related effect on body weight gain, clinical signs or ophthalmoscopic parameters was observed in any treatment group. Likewise, no treatment-related or dose-related toxic effect was found in hematology, clinical chemistry, urinalysis, blood coagulation, organ weight, gross observation or histopathology. Thus, the NOAEL for lycopene derived from recombinant Escherichia coli was at least 2000 mg/kg body weight/day.