The present trial study was intended to explore the defensive impact of Fennel oil against formaldehyde fume initiated poisonousness on serum electrolytes specifically sodium (Na+) and potassium (K+). 24 male rodents were haphazardly isolated into three gatherings (control set 1, trial set 2 and exploratory set 3). The control set 1 was taken care of with standard food supplementation with no openness while trial set 2 was presented to formaldehyde fumes and exploratory set 3 was given Fennel oil supplementation after openness to formaldehyde fumes. A huge expansion in serum sodium particle level and a reduction in serum potassium particle level was noticed separately after openness to formaldehyde fumes, while a critical lessening in serum sodium particle level and expansion in serum potassium particle level have been seen individually after supplementation of Fennel oil in contrast with formaldehyde fume uncovered rodents.