In this review the soil and environmental factors influencing B toxicity and deficiency in plants are discussed with the main emphasis being given to B toxicity. Some of the topics covered are sources of B, importance of B to plants, deficiency and toxicity criteria, factors affecting B sorption, quantification of B sorption, difficulties encountered in appraising B deficiency and toxicity limits and confusion in the specification of available B units, Eaton’s sand culture work — its assets and weaknesses, B fertilization of crops, B toxicity due to irrigation, and B equilibrium in soils. Suggested areas requiring further research are delineated. Key words: Plant boron, soil boron, boron adsorption characteristics of soil, irrigation management