The temperature dependent magnetic susceptibility, chi(T), of two samples of the S = 1 linear-chain Heisenberg antiferromagnet Ni(C2H8N2)2NO2(ClO4). known as NENP, has been measured from 400 K to 264 muK. Our measurements are in agreement with existing results of other researchers who worked above 1.2 K. Below 1.2 K, chi(T) increases with decreasing temperature. The results suggest that this increase is intrinsic to the NENP and is not a consequence of a single source of paramagnetic impurities in the samples.