Let χ n (t) = ( n i=1 X 2 i (t)) 1/2 , t ≥ 0 be a chi-process with n degrees of freedom where X i 's are independent copies of some generic centered Gaussian process X. This paper derives the exact asymptotic behaviour ofwhere T is a given positive constant, and g(·) is some non-negative bounded measurable function. The case g(t) ≡ 0 has been investigated in numerous contributions by V.I. Piterbarg. Our novel asymptotic results, for both stationary and non-stationary X, are referred to as Piterbarg theorems for chi-processes with trend.