In this paper, we consider the first-order dynamic equation as following: x ∆ (t) + m i=1 p i (t)x (τ i (t)) = 0, t ∈ [t 0 , ∞) T where p i ∈ C rd [t 0 , ∞) T , R + , τ i ∈ C rd ([t 0 , ∞) T , T) (i = 1, 2,. .. , m) and τ i (t) ≤ t, lim t→∞ τ i (t) = ∞. When the delay terms τ i (t) (i = 1, 2,. .. , m) are not necessarily monotone, we present new sufficient conditions for the oscillation of first-order delay dynamic equations on time scales.