The major objective of this paper is to determine the extent to which Nigerian firms have embraced environmental cost accounting in cost allocation. This research adopted a research survey and the main research instrument is the questionnaire. 105 Accountants from twenty-five (25) quoted manufacturing companies were the respondents for this research. The mean, standard deviation and simple percentages were used to analyze the questions while the ANOVA was used to statistically analyze the differences between means. Findings show that majority of the firms have not embraced environmental cost accounting, they still lump all indirect costs under overhead and use mostly, one absorption method which may not have any relationship with the indirect costs to apportion these costs into the product costs. The identified commonest method of overhead allocation basis is the material use. Although the treatments given to environmental costs were conventional in nature, significant differences exist among firms on the method of allocating environmental costs to products/processes. Environmental accounting can be said to be in embryonic stage in the manufacturing firms in Nigeria. This paper offers a valuable insight into the environmental cost accounting practices of Nigerian manufacturing firms. This paper will help firms to understand what environmental cost accounting is all about and how to embrace it. Keywords: Environmental accounting, Environmental cost accounting, environmental costs, conventional system.