The effects of enhanced UV_A (320-380), UV_C (280nm) and SDS, as mutagenic substances, on growth parameters and certain metabolic changes, during vegetative and flowering growth stages of garlic (Allium sativum var. Seds 40) were investigated. Root length, shoot length, fresh mass, dry mass accumulation and leaf area in garlic, treated with UV- radiation (A and C), and SDS (0.1 M and 0.3 M) as mutagenic substances, throughout the entire period of the experiment, showed significant variable changes below the control levels. Photosynthetic pigments (chl a, chl b, carotenoids, total chl a+b, and total pigment) contents of the variously treated garlic plants showed significant changes as compared with control plants throughout the duration of the experiment. The ratio of chl a / b showed variable changes in UV- and SDS- treated plants in relation to control. UV- absorbing compounds (total phenolic compounds and anthocyanins contents) of the UV- and SDS- treated garlic plants, showed significant increase above the control levels during vegetative and flowering growth stages. As compared with control nucleic acid levels, nucleic acid contents (DNA and RNA) of UV- and SDS- treated plants, at vegetative and flowering growth stages, showed significant decrease.