This work investigates the potential of metabolic stimulators, firstly to enhance the production of β-carotene, and later use of inhibitors of lycopene cyclase so as to accumulate lycopene in the fermentation medium. Various non-ionic surfactants, natural oils, stimulators such as amino-acids, tricarboxylic acid cycle (TCA) intermediates, vitamin A and antibiotics were investigated for improved production of β-carotene using the zygomycete fungus Blakeslea trispora. Span 20 at 0.2% increased the β-carotene production from 139mg/l to 318mg/l. Examination of the mycelial morphology of the B. trispora with span 20 showed a shorter mycelial length, which allowed a well-dispersed growth of B. trispora. Supplementation of the medium with 1000ppm vitamin A acetate gave highest concentration of β-carotene (830±6mg/l). Several chemical inhibitors such as imidazole, pyridine, triethylamine, piperidine, and nicotinic acid were then evaluated to block the biosynthesis at lycopene. Piperidine at 500ppm gave a 7.76-fold improvement, and produced high titers of lycopene (775±5mg/l) in a medium supplemented with vitamin A acetate.