A van der Pol equation with sinusoidal forcing term is analyzed with singular perturbation methods for large values of the parameter. Asymptotic approximations of (sub)harmonic solutions with period
T
=
2
π
(
2
n
−
1
)
,
n
=
1
,
2
,
.
.
.
T = 2\pi \left ( {2n - 1} \right ),n = 1, 2, ...
are constructed under certain restricting conditions for the amplitude of the forcing term. These conditions are such that always two solutions with period
T
=
2
π
(
2
n
±
1
)
T = 2\pi \left ( {2n \pm 1} \right )
coexist.